Liquid crystal display device and thin film transistor substrate

ABSTRACT

In a vertically aligned liquid crystal display device for controlling liquid crystal molecules alignment in voltage application by providing linear structures or linear slits consisting of a plurality of constituent units to at least one of a pair of substrates having an electrode thereon, there is provided alignment controlling means for forming an alignment singular point s=−1 of liquid crystal molecules at an intersecting point between the structures on the pixel electrode or the slits in the electrode and an edge of a pixel electrode on one of the substrates.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a liquid crystal display (LCD)device and a thin film transistor substrate and, more particularly, a VA(Vertically aligned) mode liquid crystal display device and a thin filmtransistor substrate.

[0003] 2. Description of the Prior Art

[0004] The liquid crystal display device is employed in variouselectronic devices, e.g., is employed as not only the display of themobile computer, but also the display of the desk-top computer, thedisplay of the television, the projector, the personal digital assistant(PDA), etc.

[0005] The normal TN (Twisted Nematic) mode liquid crystal displaydevice has such a structure that the liquid crystal is sealed betweentwo transparent substrates. Out of two surfaces of these transparentsubstrates opposing to each other, the common electrode, the colorfilter, the alignment film, etc. are formed on one surface side, and thethin film transistor (TFT), the pixel electrodes, the alignment film,etc. are formed on the other surface side. Also, polarizing plates arestuck on the opposing surfaces and the opposite side surfaces of thetransparent substrates respectively. These two polarizing plates arearranged such that, for example, their polarization axes can intersectperpendicularly to each other. In this case, two polarizing plates givethe light display (white display) to transmit the light in the conditionthat the voltage is not applied between the pixel electrode and thecommon electrode, while they give the dark display (black display) tocut off the light in the condition that the voltage is applied. Incontrast, if the polarization axes of two polarizing plates are arrangedin parallel with each other, two polarizing plates give the dark displayin the condition that the voltage is not applied between the pixelelectrode and the common electrode, while they give the light display inthe condition that the voltage is applied. In the following description,the substrate on which TFT and the pixel electrodes are formed is calledthe TFT substrate, while the substrate on which the color filters andthe common electrode are formed is called the opposing substrate.

[0006] The TN mode liquid crystal display device has such drawbacks thatthe viewing angle is narrow and the resolution is not sufficient.

[0007]FIGS. 1A to 1C are views showing these drawbacks. FIG. 1A showsthe state to display the white by not applying the voltage between twoelectrodes 101, 102, FIG. 1B shows the state to display the half tone(gray) by applying the intermediate voltage V1 between two electrodes101, 102, and FIG. 1C shows the state to display the black by applyingthe predetermined voltage V2 between two electrodes 101, 102.

[0008] In FIGS. 1A to 1C, alignment films 103, 104 are formed on theopposing surfaces of two electrodes 101, 102 to differentiate theiralignment directions by 90° (degrees) respectively. Also, although notshown, the polarizing plates are arranged on respective outsides of twoelectrodes 101, 102 in the condition that their linearly polarizeddirections are twisted mutually by 90 degrees. In this case, actuallyliquid crystal molecules L shown in FIGS. 1A to 1C are twisted incompliance with the alignment direction of the alignment films 103, 104,but they are illustrated herein not to take account of the twist, forthe convenience of explanation.

[0009] Meanwhile, as shown in FIG. 1A, in the condition that the voltageis not applied, the liquid crystal molecules L are aligned in the samedirection to have a very small tilt angle (about 1 degree to 5 degrees).In this state, the display looks like almost white from all directions.

[0010] Also, as shown in FIG. 1C, in the condition that the voltage V2is applied, the liquid crystal molecules L are aligned in theperpendicular direction to the alignment films 103, 104 except theneighborhood of their surfaces. Since the incident linearly polarizedlight is intercepted by the plate, the display looks like the black fromthe outside. At this time, since the light irradiated obliquely into oneelectrode 101 passes obliquely to the direction of the liquid crystalmolecules L aligned in the vertical direction to thus twist itspolarization direction to some extent, the display looks like not theperfect black but the half tone (gray) from the outside.

[0011] In addition, as shown in FIG. 1B, in the condition that theintermediate voltage V1 lower than the state in FIG. 1C is applied, theliquid crystal molecules L positioned in vicinity of the alignment films103, 104 are also aligned in the horizontal direction, but the liquidcrystal molecules L rise obliquely in the middle area of the cell.Therefore, the double refraction (birefringence) property of the liquidcrystal is lost in some degree to lower the transmittance and thus thehalf tone (gray) display appears. However, this is true of only thelight L1 that is irradiated vertically to the liquid crystal panel. Thelight that is irradiated obliquely to the surface of one electrode 101exhibits different behaviors when the display is viewed from the leftand right directions in FIG. 1B.

[0012] In other words, in FIG. 1B, the direction of the liquid crystalmolecules L becomes parallel with the light L2 that is directed from thelower right to the upper left. Therefore, since the liquid crystal Lseldom exhibits the double refraction effect, the display looks like theblack when it is viewed from the left side. On the contrary, thedirection of the liquid crystal molecules L becomes perpendicular to thelight L3 that is directed from the lower left to the upper right.Therefore, since the liquid crystal L exhibits greatly the doublerefraction effect to the incident light to twist the incident light, thedisplay looks like a color close to the white. That is, the displayintensity is changed according to the viewing angle, and this aspect isthe biggest drawback of the TN mode liquid crystal display device.

[0013] For this reason, as the mode that can improve the viewing anglecharacteristic without reduction of the response speed, the VA(Vertically Aligned) mode using the vertical alignment films has beenproposed.

[0014]FIGS. 2A to 2C are views showing the VA mode. The VA mode uses thenegative type liquid crystal material and the vertical alignment filmsin combination.

[0015] First, as shown in FIG. 2A, when the voltage is not applied, theliquid crystal molecules L are aligned in the vertical direction toprovide the black display. In the VA mode, the vertically aligningprocess is applied to the alignment films 103, 104.

[0016] Also, as shown in FIG. 2C, when the predetermined voltage V2 isapplied between two electrodes 101, 102, the liquid crystal molecules Lare aligned in the horizontal direction to provide the while display.The VA mode has the high display contrast, the quick response speed, andthe visual characteristic in the white display and the black displayrather than the TN mode.

[0017] In addition, as shown in FIG. 2B, when the predetermined voltageV1 smaller than that in the white display is applied between twoelectrodes 101, 102, the liquid crystal molecules L are aligned in theoblique direction. In this case, the light that is perpendicular to thesurface of the electrode 101 is displayed as the half tone on thedisplay panel. However, in FIG. 2B, the liquid crystal molecules L areparallel with the light L2 directed from the lower right to the upperleft. Accordingly, since the liquid crystal molecules L seldom exhibitsthe double refraction effect, the display looks like the black if it isviewed from the left side. In contrast, the liquid crystal molecules Lare vertical to the light L3 directed from the lower left to the upperright. Accordingly, since the liquid crystal molecules L exhibitsgreatly the double refraction effect to the incident light to twist theincident light, the display that is close to the white is given.

[0018] In this manner, since the liquid crystal molecules positioned inthe neighborhood of the alignment films become substantially verticalwhen the voltage is not applied, the VA mode has the especially highcontrast and also is excellent in the viewing angle characteristicrather than the TN mode. However, the VA mode has the problem similar tothe TN mode, i.e., when the half tone display is performed in the VAmode, the display intensity is changed if the viewing angle is changed.Thus, the VA mode is still not enough in the aspect of the viewing anglecharacteristic.

[0019] In Patent Application Hei 10-185836, the applicant of thisapplication discloses the configuration in which vertical alignment inthe prior art is used, the liquid crystal material having the negativedielectric anisotropy, so-called negative type liquid crystal, is sealedbetween the electrodes, and the domain defining means for defining theliquid crystal molecules to differentiate their tilt directions in aplurality of regions in one pixel when the voltage is not applied isprovided.

[0020]FIGS. 3A to 3C are views showing the visual characteristicimproving principle by using alignment division. In this case, thestructure is employed in which the slit S is formed in one pixelelectrode 111 on the first substrate side as the domain defining meansand the projection P is provided in one pixel on the electrode 112 onthe second substrate side.

[0021] As shown in FIG. 3A, when the voltage is not applied, the liquidcrystal molecules are aligned perpendicularly to the substrate surface.Also, as shown in FIG. 3C, when the predetermined voltage V2 is appliedbetween the opposing electrodes 111, 112, the liquid crystal moleculesare aligned in parallel with the substrate surface to provide the whitedisplay.

[0022] In addition, as shown in FIG. 3B, when the intermediate voltageV1 is applied between the opposing electrodes 111, 112, the electricfield that is oblique to the substrate surface is generated due to theslit (electrode edge portion) S. Also, the liquid crystal molecules L inthe neighborhood of the surface of the projection P are slightly tiltedfrom the state when no voltage is applied. The tilt directions of theliquid crystal molecules L are decided by the influence of inclinedsurfaces of the projection P and the oblique electric field. Thus, thealignment directions of the liquid crystal molecules 113 are divided inthe middle of the projection P and in the middle of the slit portionills respectively.

[0023] At this time, since the liquid crystal molecules L are slightlytilted, for example, the light L1 that is transmitted from the bottom ofthe substrate to the top is affected slightly by the double refractionto suppress the transmission. Thus, the half tone display of gray can beobtained. The light L2 transmitted from the lower right to the upperleft is hard to transmit in the area in which the liquid crystalmolecules L are tilted to the left direction, but such light L2 is veryeasy to transmit in the area in which the liquid crystal molecules L aretilted to the right direction. Thus, the half tone display of gray canbe obtained as the average. In addition, the light L3 transmitted fromthe lower left to the upper right exhibits the gray display based on thesimilar principle. As a result, the uniform half tone display can beobtained in all directions in one pixel.

[0024] Therefore, in FIG. 3B, the good display that has the smallviewing angle dependency can be obtained in all the black, half tone,and white display states.

[0025] In FIGS. 3A to 3C, the slit S is formed in one pixel electrode111 on the first substrate side as the domain defining means, and theprojection P is provided in one pixel on the electrode 112 on the secondsubstrate side. But such structure may be accomplished by other means.Such new VA mode is referred to as the MVA (Multi-domain VerticalAlignment) mode in the following.

[0026]FIGS. 4A to 4C are views showing examples for implementing thedomain defining means.

[0027]FIG. 4A shows an example in which the domain defining means isimplemented only by using the electrode shapes, FIG. 4B shows an examplein which shapes of the substrate surfaces are designed, and FIG. 4Cshows an example in which shapes of the electrodes and the substratesurfaces are designed. Although the alignments shown in FIGS. 3A to 3Ccan be obtained in all these examples, respective structures areslightly different.

[0028] Next, the case where projections are provided on the opposingsurfaces of two substrates, as shown in FIG. 4B, will be explained as anexample hereunder.

[0029] In FIG. 4B, projections P1, P2 for dividing the alignmentdirections alternatively are formed on the electrodes 111, 112 on theopposing surfaces of two substrates, and also vertical alignment films113, 114 are provided on the inner surfaces of them. The verticalaligning process is applied to the vertical alignment films. The liquidcrystal injected between two substrates is the negative type one. Whenno voltage is applied, the liquid crystal molecules L are alignedperpendicularly to the substrate surface on the vertical alignmentfilms. Since the liquid crystal molecules L tend to be alignedperpendicularly to the inclined surfaces of the projections P1, P2, suchliquid crystal molecules L on the projections P1, P2 are also tilted.However, since the liquid crystal molecules L are aligned almostperpendicularly to the substrate surface in most areas except for theprojections P1, P2 when no voltage is applied, the good black displaycan be obtained, as shown in FIG. 3A.

[0030] When the voltage is applied, the liquid crystal molecules L areparallel with the substrate (the electric field is perpendicular to thesubstrate) in areas in which the projections P1, P2 are not provided,but such liquid crystal molecules L are tilted in vicinity of theprojections P1, P2. In other words, when the voltage is applied, theliquid crystal molecules L are tilted in response to the intensity ofthe electric field but the electric field is directed perpendicularly tothe substrate. Therefore, unless the tilt direction of the Liquidcrystal molecules L is defined by the rubbing, the liquid crystalmolecules L may take all directions of 360 degrees as the tilted azimuthto the electric field. Since the electric field is inclined in thedirection parallel with the inclined surfaces of the projections P1, P2on the projections P1, P2, the liquid crystal molecules L are tilted inthe direction perpendicular to the electric field when the voltage isapplied. This direction coincides with the original direction inclinedby the projections P1, P2, and thus the liquid crystal molecules L arealigned more stably. In this manner, the projections P1, P2 can providethe stable alignment by both effects of their inclination and theelectric field on the inclined surface. In addition, if the largevoltage is applied, the liquid crystal molecules L are aligned in almostparallel with the substrate.

[0031] As described above, the projections P1, P2 can perform a role ofthe trigger that decides the alignment azimuth of the liquid crystalmolecules L when the voltage is applied.

[0032] In FIG. 4A, slits S1, S2 are provided on both or either ofelectrodes 111, 112. The vertical aligning process is applied to thealignment films 113, 114, and the negative type liquid crystal is sealedbetween the substrates. The liquid crystal molecules L are alignedperpendicularly to the substrate surface when no voltage is applied,whereas the electric field is generated at the slits (electrode edgeportions) S1, S2 in the oblique direction to the substrate surface whenthe voltage is applied. The tilt directions of the liquid crystalmolecules L are decided by the influence of this oblique electric field,and thus the alignment directions of the liquid crystal molecules aredivided in the right and left directions, as shown in FIG. 4A.

[0033]FIG. 4C shows an example in which the modes in FIG. 4A and FIG. 4Bare combined together. The slits S are formed in one electrode 111 whilethe projections are provided on the other electrode 112. Though examplesfor implementing three domain defining means are illustrated as above,various variations may be adopted.

[0034]FIG. 5 is a plan view showing positional relationships among buslines, projections, pixels, and electrodes in the liquid crystal displaypanel in which the alignment of the liquid crystal molecules are dividedinto four directions. FIG. 6 is a sectional view taking along a I-I linein FIG. 5.

[0035] In FIG. 5 and FIG. 6, a plurality of gate bus lines 122 extendingin the X direction (the lateral direction in FIG. 5 and FIG. 6) areformed on the TFT substrate 121 at a distance along the Y direction (thelongitudinal direction in FIG. 5 and FIG. 6). Also, capacitive bus lines123 extending in the X direction are formed between the gate bus lines122. Auxiliary capacitive branch lines 123 a that have a length not totouch the gate bus lines 122 are formed from the capacitive bus lines123 in the Y direction so as to oppose to a part of drain bus lines(also called data bus lines), described later.

[0036] The gate bus lines 122 and the capacitive bus lines 123 arecovered with a first insulating film 124. Then, a plurality of drain buslines 125 extending in the Y direction are formed in the X direction onthe first insulating film 124 at a distance. The TFTs 126 are formed tocorrespond to crossing portions between the gate bus lines 122 and thedrain bus lines 125. The TFT 126 has a semiconductor layer 126 a formedon the gate bus line 122 via the first insulating film 124, a drainelectrode 126 d formed on the semiconductor layer 126 a, and a sourceelectrode 126 s formed on the semiconductor layer 126 a. The drainelectrode 126 d is connected to the neighboring drain bus lines 125. Thedrain bus lines 125 and the TFTs 126 are covered with a secondinsulating film 127.

[0037] A pixel electrode 128 made of ITO (indium-tin oxide) is formed onthe second insulating film 127 and in the area surrounded by two drainbus lines 125 and two gate bus lines 122. The pixel electrode 128 isconnected to the source electrode 126 s via a hole in the secondinsulating film 127.

[0038] The capacitive bus line 123 is hold at a constant potential. Ifthe potential of the drain bus line 125 is varied, the potential of thepixel electrode 128 is also varied based on the capacitive coupling dueto the stray capacitance. According to the configuration in FIG. 6,since the pixel electrode 128 is connected to the capacitive bus line123 via auxiliary capacitances, variation in potential of the pixelelectrode 128 can be reduced.

[0039] In FIG. 6, a color filter 132, a black matrix 133, a commonelectrode 134, and an alignment film 135 are formed in sequence on anopposing substrate 131 opposing to the TFT substrate 121.

[0040] Also, projections 130, 136 that have zig-zag bending patterns toextend in the Y direction are formed on the opposing surfaces of theopposing substrate 131 and the TFT substrate 121 respectively. A bendingangle of the bending pattern is roughly 90 degrees.

[0041] The projections 130 formed on the TFT substrate 121 side arealigned at an equal interval in the X direction, and their bendingpoints are positioned in the almost center of the gate bus lines 122.The projections 136 formed on the opposing substrate 131 have a patternsubstantially similar to the projections 130 formed on the TFT substrate121, and are formed on the common electrodes 134 such that they arepositioned in the almost middle portion between a plurality ofprojections 130 on the TFT substrate 121.

[0042] The projections 130 on the TFT substrate 121 side and the pixelelectrodes 128 are covered with the alignment film 129, while theprojections 136 on the opposing substrate 131 side are also covered withanother alignment film 135. Both the projections 130 on the TFTsubstrate 121 side and the projections 136 on the opposing substrate 131side intersect with edges of the pixel electrodes 128 at an angle of 45degrees respectively.

[0043] Also, polarizing plates (not shown) are arranged on the surfacesof the TFT substrate 121 and the opposing substrate 131, which do notput the liquid crystal material between them, respectively. Thesepolarizing plates are arranged such that their polarization axesintersect with linear portions of the projections 130, 136 by 45 degreesto form cross-nicol. That is, the polarization axis of one polarizingplate is parallel with the X direction in FIG. 6 and the polarizationaxis of the other polarizing plate is parallel with the Y direction inFIG. 6.

[0044] The TFT substrate 121 and the opposing substrate 131 are arrangedin parallel at a distance mutually, and the liquid crystal material 139is filled into a space between them. The liquid crystal material 139having the negative dielectric anisotropy is employed, as describedabove. The projections 130, 136 are formed of material that has thedielectric constant equivalent to or less than that of the liquidcrystal material 139.

[0045] Next, the alignment of the liquid crystal molecules L when theintermediate voltage is applied to the pixel electrodes will beexplained, by taking as an example the case where the slits are formedin the pixel electrode, hereunder.

[0046]FIG. 7 is a plan view showing positional relationship among thegate bus lines, the drain bus lines, the capacitive bus lines, and thepixel electrode 128 formed on the TFT substrate on which the slits S areprovided on the pixel electrode in place of the projections 130 shown inFIG. 5.

[0047] In FIG. 7, the pixel electrode 128 a is divided into a pluralityof areas by a plurality of slits S passing between upper projections 136a. These areas are conductively connected mutually by connectingportions 128 b that are formed to cross the slits S. Two slits S formedin the neighborhood of the center of the pixel electrode 128 a areintersected with each other at the edge portion of the pixel electrode128 a.

[0048] Then, when the intermediate voltage is applied to the pixelelectrode 128 a, the liquid crystal molecules L on the pixel electrode128 a are tilted to the surface of the pixel electrode 128 a. The liquidcrystal molecule L in FIG. 7 is indicated by a circular cone. A vertexof the circular cone indicates a position of one end of the liquidcrystal molecule on the TFT substrate side, and a base of the circularcone indicates a position of the other end of the liquid crystalmolecule. Four types of the tilt direction of the liquid crystalmolecule L are given based on the principle shown in FIG. 4.

[0049] As described above, the MVA mode is the mode in which the liquidcrystals having the negative dielectric anisotropy are alignedsubstantially perpendicularly to the substrate surface. Since the MVAmode can have the high contrast and can improve the visualcharacteristic without reduction of the switching speed, its displayquality is good. In addition, the viewing angle characteristic can beimproved much more by using the domain defining means.

[0050]FIG. 8 is a sectional view showing another MVA liquid crystaldisplay device in the prior art. First projections 167 are formed on theopposing surface of a glass substrate 151, and second projections 168are formed on the opposing surface of a glass substrate 186. The firstprojections 167 and the second projections 168 extend in the directionperpendicular to the sheet of FIG. 8, and are arranged alternately alongthe lateral direction in FIG. 8. A vertical alignment film 178 is formedon the opposing surfaces of the glass substrates 151, 186 respectivelyto cover the projections 167, 168.

[0051] Liquid crystal material 179 containing liquid crystal molecules180 is filled between the glass substrate 151 and the glass substrate186. The liquid crystal molecules 180 have the negative dielectricanisotropy. The dielectric constant of the projections 167, 168 is lowerthan that of the liquid crystal material 179. Polarizing plates 181, 182are cross-nicol-arranged on the outside of the glass substrate 151 andthe glass substrate 186 respectively. Since the liquid crystal molecules180 are aligned vertically to the substrate surface when the voltage isnot applied, the good dark state can be obtained.

[0052] When the voltage is applied between the substrates, equipotentialsurfaces indicated by a broken line 166 appear. Since the dielectricconstant of the projections 167, 168 is smaller than that of the liquidcrystal layers, the equipotential surfaces 166 in the neighborhood ofthe side surfaces of the projections 167, 168 are inclined to come downin the projections. Therefore, the liquid crystal molecules 180 a in theneighborhood of the side surfaces of the projections 167, 168 are tiltedto become parallel to the equipotential surfaces 166. The peripheralliquid crystal molecules 180 a are tilted by the influence of thetilting of the liquid crystal molecules 180 a. For this reason, theliquid crystal molecules 180 between the first projections 167 and thesecond projections 168 are aligned such that their major axis (director)is inclined right-upward in FIG. 8. The liquid crystal molecules 180positioned on the left side rather than the first projections 167 andthe liquid crystal molecules 180 positioned on the right side ratherthan the second projections 168 are aligned such that their major axis(director) is inclined right-downward in FIG. 8.

[0053] In this manner, a plurality of domains in which the tiltdirections of the liquid crystal molecules are different are defined inone pixel. The first projections 167 and the second projections 168define boundaries of the domains. Two type domains can be formed byarranging the first projections 167 and the second projections 168 inparallel with the substrate surface mutually. Four type domains can beformed in total by bending patterns of these projections by 90 degrees.Since plural domains are formed in one pixel, the visual characteristicin the half tone display state can be improved.

[0054] The inventors of the present invention point out that the aboveliquid crystal display device in the prior art has problems described inthe following.

[0055] The MVA mode liquid crystal display device can achieve the highpicture quality, the high reliability, and the high productivity.However, the VA mode has essentially such a nature that it easilyaccepts the influence of the electric field because of its weakanchoring force in contrast to the horizontally aligned mode such as theTN mode, and thus the MVA mode partakes of such nature of the VA mode.

[0056] Accordingly, as shown in FIGS. 9A and 9B, the alignment state ofthe liquid crystal molecules L around the pixel electrode 128 is changedbecause of changes of the gate bus line potential Egc and the drain busline potential (data voltage) Egs in some case. Such phenomenon occurssimilarly in the case of the TN mode, nevertheless the phenomenon isready to occur in the VA mode rather than the TN mode.

[0057] Also, as the phenomenon peculiar to the MVA mode, sometimes theprojections are charged under various conditions such as the drivingstate. At this time, the alignment of the liquid crystals at theintersecting portions between the drain bus lines and the gate bus linesis changed by the influence of the charge of the projections.

[0058] When the alignment around the pixel is changed, values of thestray capacitances, e.g., a gate-common electrode capacitance Cgc, agate-source capacitance Cgs, a drain-common electrode capacitance Cdc,etc. are also changed correspondingly. As a result, the potential of thepixel electrode 126 s is also changed by the capacitive coupling.Normally the potential variation of the pixel electrode is reduced bythe auxiliary capacitance, but such variation cannot be perfectlycompensated in some cases. The potential variation of the pixelelectrode is easily caused if the auxiliary capacitance is reduced toincrease the aperture ratio especially. If the potential of the pixelelectrode is varied, the flicker appears on the screen.

[0059] It may be considered that the auxiliary capacitance is increasedto such extent that the potential variation of the pixel electrode canbe eliminated completely. If so, the aperture ratio is reducedcorrespondingly.

[0060] Next, generation of residual images in the MVA liquid crystaldisplay device will be explained hereunder.

[0061] The generation of residual images in the liquid crystal displaydevice is caused by the abnormality of the response speed. This isbecause the domain control direction on the above projections on theelectrode and on the above slits is not defined.

[0062] Such unstability of the domain control direction is generated dueto variation in cell thickness, etc. Hence, the liquid crystal displaydevice in which the residual images are caused is not forwarded as thedefective product.

[0063] As the result of the examination to check the cause for thelong-time remaining residual images, followings become apparent.

[0064] In other words, as shown in FIGS. 10A and 10B, in the liquidcrystal display device employing the configuration in which a pluralityof projections or slits are formed on the electrodes, it can beunderstood that, if there is a difference between the domain state whenthe display is changed from the black to the white and the domain statewhen the display is changed from the half tone to the white, thelong-time remaining residual images are generated.

[0065] In FIG. 10A, the number of domains on the slits S after thedisplay is changed from the black to the white are six because thedomain is divided by boundaries at middle positions (center positions ofthe slits S) between all the connecting portions 128 b of the pixelelectrode 128 a. Therefore, the liquid crystal molecules L in theneighborhood of the slits S are aligned in the perpendicular directionto the straight portions of the slits S.

[0066] In contrast, in FIG. 10B, the number of domains on the slits Safter the display is changed in the order of the black, the half tone,and the white are two or four because the domain is divided byboundaries between a part of the connecting portions 128 b. Therefore,there exists an area in which the domains are not changed by boundariesbetween the connecting portions 128 b and their middle portions. Theliquid crystal molecules L in vicinity of the slits S are alignedobliquely to the straight portions of the slits S in this area.

[0067] One of the causes may be considered as follows. That is, sincethe voltage is not sufficiently applied to the liquid crystal moleculesL on the projections 130 or the slits S in the half tone display, theliquid crystal molecules L are aligned almost perpendicularly to thesubstrate surface, as shown in FIG. 11. Thus, influences of the electricfield at the edge of the pixel electrode 128 a and the alignment of thedisplay domains being affected by such electric field affect the dividedportions of the alignment controlling means as the connecting portions.As a result, the alignment control effect achieved by dividing thealignment controlling means cannot be sufficiently performed. In otherwords, when the liquid crystal molecules L on the slits S or theprojections 130 are aligned perpendicularly in the half tone display,such neighboring liquid crystal molecules L are affected by the electricfield at the edges of the pixel electrode 128 a and then tilted to thestraight portions of the slits S or the projections 130.

[0068] Accordingly, when the display is changed from the half tonedisplay to the white display, the domain {circle over (3)} shown in FIG.10A disappears to connect the domains {circle over (2)} and {circle over(4)}, and then the domain {circle over (5)} disappears to connect thedomains {circle over (4)} and {circle over (6)}. As a result, as shownin FIG. 10B, the right-upward directed domains are connected and theleft-downward directed domains are disappeared, so that the domains onthe slits S after the white display are reduced into two domains {circleover (1)} and {circle over (2)}.

[0069] As another one of the causes for generating the residual images,it may be considered that the bending portions of the patterns of theprojections 130 or the slits S of the alignment controlling means arearranged at the edges of the pixel electrode 128 a. The alignment statesof the liquid crystal molecules L at the bending portions are any ofthree types shown in FIGS. 12A to 12C.

[0070] However, the alignment at the bending portions becomes as shownin FIG. 12C since it is affected by the influence of the alignment bythe edges of the pixel electrode 128 a. As a result, as indicated by adot-dash line in FIG. 13, the alignment control direction by the edgesof the pixel electrode 128 a is extended into the pixel. Since thisextension affects the alignment of the domains on the slits S in thecase of the half tone display, the alignment control effect given bydividing the alignment controlling means cannot sufficiently be broughtabout.

[0071] Also, as shown in FIG. 14A and FIG. 14B, in the TFT substrate,sometimes the area in which a plurality of electrodes are stacked,especially the pixel electrode 128 a and the capacitance electrode(capacitive bus line) 123 are punched through the insulating filmbetween them to generate the short-circuit. At this time, in the liquidcrystal display device having the structure in which the pixel electrode128 a is divided into a plurality of areas by using the slits S as thealignment controlling means and then these areas are electricallyconnected by the connecting portions 128 b, as indicated by an X mark inFIGS. 14A and 14B, the short-circuited area is disconnected from otherareas by cutting off the connecting portions 128 b near the TFT 126 inthe area of the pixel electrode 128 a, that is short-circuited to thecapacitive bus line 123, so that the liquid crystal molecules in thepixel can be partially driven.

[0072] However, since the area that is short-circuited to the capacitivebus line 123 of the pixel electrode 128 a is positioned in the center ofthe pixel, merely the half area or less of the pixel electrode 128 a canbe driven, as indicated by a dot-dash line in FIG. 14A, whereby thispixel area acts as the point defect failure to lower yield of thedevice.

[0073] When the voltage is not applied, the liquid crystal molecules invicinity of the edges of the projections 167, 168 in the MVA liquidcrystal display device in the prior art shown in FIG. 8 are alignedalmost perpendicularly in the area in which the projections 167, 168 arenot formed. However, the liquid crystal molecules in the neighborhood ofthe edges of the projections 167, 168 are affected by the inclinedsurfaces of the projections and thus tilted to the substrate surface.Therefore, the double refraction effect appears against the light beingtransmitted in the thickness direction of the liquid crystal layer.Because of this double refraction effect, the light is transmittedslightly when the display is to be in the dark state, and thus loweringof the contrast is brought out.

[0074] The leakage of light in the dark state can be prevented bycovering the areas located in the neighborhood of the inclined surfacesof the projections with a light-shielding film. Nevertheless, if suchlight-shielding film is provided, the light is shielded even in thelight state and thus reduction of the transmittance (the aperture ratio)is brought about.

[0075] Also, in the MVA liquid crystal display device shown in FIG. 8 inthe prior art, the liquid crystal molecules 180 are tilted when thevoltage is applied, but the tilt directions of the liquid crystalmolecules in the area located far from the projections 167, 168 are notdirectly decided. That is, the liquid crystal molecules 180 a in theneighborhood of the projections 167, 168 are tilted and the tilt ispropagated sequentially up to the area far from the projections 167,168. In this manner, the tilt directions of the liquid crystal molecules180 in the area far from the projections 167, 168 are indirectlydecided. Since distortion of the electric field is small at the time ofthe half tone display state, the propagation speed of the tilt of theliquid crystal molecules is lowered. Therefore, the response from thedark state to the half tone state is delayed.

[0076] Also, the transmission loss of the light is ready to generate inthe neighborhood of the projections provided in the MVA liquid crystaldisplay device. Therefore, there is such a tendency that thetransmittance (aperture ratio) is reduced in contrast to the TN modeliquid crystal display device. In case the liquid crystal display deviceis used as the floor type one, the reduction in the transmittance doesnot become a large issue. Nevertheless, in order to install the liquidcrystal display device onto the mobile device, it is desired to enhancethe transmittance.

[0077] Upon the progress of the lower consumption power of the liquidcrystal display device, it is one of important subjects to increase theaperture ratio. In the MVA mode liquid crystal display device, thealignment division (multi-domain) can be accomplished by forming thedomain defining projections (so-called banks) on the TFT substrate andthe opposing substrate respectively, and thus the good viewing anglecharacteristic and the good picture quality can be derived. In thiscase, the aperture ratio is reduced because of the projections in thepixel area.

SUMMARY OF THE INVENTION

[0078] It is an object of the present invention to provide a liquidcrystal display device capable of achieving a good picture quality.

[0079] The above subjects can be overcome by providing, as shown in FIG.25, a vertically aligned liquid crystal display device for controllingliquid crystal molecules alignment in voltage application by providinglinear structures or linear slits consisting of a plurality ofconstituent units to at least one of a pair of substrates having anelectrode thereon, comprising: alignment controlling means for formingan alignment singular point s=−1 of liquid crystal molecules at anintersecting point between the structures on the electrode or the slitsin the electrode and an edge of a pixel electrode on one of thesubstrates.

[0080] According to the present invention, in the liquid crystal displaydevice having at least one of the structures on the electrode, that isused as the domain defining means, or the slits in the electrode, thealignment singular point s=−1 or s=+1 of the liquid crystal molecules isformed in the neighborhood of the intersecting portion between theprolonged line of the structures or the slits and the edge of the pixelelectrode.

[0081] As for the change of the domains of the liquid crystal moleculeson the slits if the present invention is applied, as shown in FIG. 32A,for example, when the display is changed from the black display to thewhite display, the number of domains divided by the connecting portionson the slit is eight such as {circle over (1)} to {circle over (8)}.Also, according to FIG. 32A, the domains {circle over (8)} and {circleover (9)} are increased in number rather than FIG. 10A indicating theproblem in the prior art. This is because the singular point s=−1 of thealignment vector is formed at the edge of the pixel electrode. Then, asshown in FIG. 32B, when the display is changed from the black display tothe white display via the half tone display, the domains {circle over(6)} and {circle over (8)} are connected and thus the domain {circleover (7)} disappears. In other words, the change of domains on the slitscan be suppressed at a very small level rather than FIG. 10A in theneighborhood of the edge of the pixel electrode.

[0082] Accordingly, difference of the domain states between the whitemonitored when the display of the pixel is changed from the blackdisplay to the white display and the white monitored when the display ofthe pixel is changed from the half tone display to the white display canbe reduced to an unobtrusive level, so that the domain change can bereduced up to a undistinguishable level as the residual image.

BRIEF DESCRIPTION OF THE DRAWINGS

[0083]FIGS. 1A to 1C are views showing changes in images according to aviewing angle of the TN mode liquid crystal display device in the priorart;

[0084]FIGS. 2A to 2C are views showing driving states of the VA liquidcrystal display device in the prior art;

[0085]FIGS. 3A to 3C are views showing an effect of alignment divisionin the VA mode in the prior art;

[0086]FIGS. 4A to 4C are views showing various modes of alignmentdivision in the prior art;

[0087]FIG. 5 is a plan view showing a pixel portion in the MVA mode inthe prior art;

[0088]FIG. 6 is a sectional view showing the pixel portion in the MVAmode in the prior art, taking along a I-I line in FIG. 5;

[0089]FIG. 7 is a plan view slowing a pixel portion in the MVA mode inthe prior art;

[0090]FIG. 8 is a sectional view showing an MVA liquid crystal displaydevice in the prior art;

[0091]FIGS. 9A and 9B are views showing an OFF state and an ON state ofan MVA liquid crystal panel in the prior art;

[0092]FIGS. 10A and 10B are views showing changes in the alignmentdirection of liquid crystal molecules in the MVA liquid crystal panel inthe prior art;

[0093]FIG. 11 is a view showing the alignment direction of the liquidcrystal molecules in half tone display of the MVA mode in the prior art;

[0094]FIGS. 12A to 12C are views showing combinations of the alignmentdirection of the liquid crystal molecules on a slit on a pixel electrodein the MVA mode in the prior art;

[0095]FIG. 13 is a view showing the alignment direction of the liquidcrystal molecules in vicinity of an edge of the pixel electrode afterthe liquid crystal display in the VA mode in the prior art is changedfrom the half tone display to the white display;

[0096]FIG. 14A is a plan view showing a cut-off state of the pixelelectrode in the VA mode in the prior art, and FIG. 14B is an equivalentcircuit diagram in this state;

[0097]FIG. 15 is a plan view showing arrangement of domain definingmeans in a pixel area according to a first embodiment of the presentinvention;

[0098]FIG. 16 is a plan view showing the pixel area in which adielectric structure and projections are formed, according to the firstembodiment of the present invention;

[0099]FIG. 17 is a sectional view showing the pixel area according tothe first embodiment of the present invention, taken along a II-II linein FIG. 16;

[0100]FIG. 18 is a sectional view showing the pixel area according tothe first embodiment of the present invention, taken along a III-IIIline in FIG. 16;

[0101]FIG. 19 is a sectional view showing the pixel area according tothe first embodiment of the present invention, taken along a IV-IV linein FIG. 16;

[0102]FIGS. 20A and 20B are sectional views showing an operation in thepixel area according to the first embodiment of the present invention;

[0103]FIG. 21 is a plan view showing a pixel area of a liquid crystaldisplay device according to a second embodiment of the presentinvention;

[0104]FIG. 22 is a sectional view showing the pixel area of the liquidcrystal display device according to the second embodiment of the presentinvention, taken along a V-V line in FIG. 21;

[0105]FIG. 23 is a sectional view showing a TFT and its neighboring areaaccording to the second embodiment of the present invention, taken alonga VI-VI line in FIG. 21;

[0106]FIG. 24 is a sectional view showing a pixel area of a liquidcrystal display device according to a third embodiment of the presentinvention;

[0107]FIG. 25 is a plan view showing the pixel area of the liquidcrystal display device according to the third embodiment of the presentinvention;

[0108]FIGS. 26A and 26B are views showing the alignment direction of theliquid crystal molecules at an alignment singular point according to thethird embodiment of the present invention;

[0109]FIG. 27 is a plan view showing a pixel area of a liquid crystaldisplay device according to a fourth embodiment of the presentinvention;

[0110]FIG. 28 is a sectional view showing the pixel area of the liquidcrystal display device according to the fourth embodiment of the presentinvention, taken along a VII-VII line in FIG. 27;

[0111]FIG. 29 is a plan view showing a pixel area of a liquid crystaldisplay device according to a fifth embodiment of the present invention;

[0112]FIG. 30 is a plan view showing another pixel area of the liquidcrystal display device according to the fifth embodiment of the presentinvention;

[0113]FIG. 31A is a plan view showing a pixel area of a liquid crystaldisplay device according to a sixth embodiment of the present invention,and FIG. 31B is a view showing connection between areas in the pixelelectrode in the pixel area;

[0114]FIGS. 32A and 32B are views showing an example of an effectachieved by the sixth embodiment of the present invention;

[0115]FIG. 33 is a plan view showing an MVA liquid crystal displaydevice according to a seventh embodiment of the present invention;

[0116]FIG. 34 is a sectional view showing a TFT portion of the MVAliquid crystal display device according to the seventh embodiment of thepresent invention;

[0117]FIG. 35 is a sectional view showing a pixel electrode portion ofthe MVA liquid crystal display device according to the seventhembodiment of the present invention;

[0118]FIG. 36 is a sectional view showing a substrate and a mask toexplain a method of manufacturing the MVA liquid crystal display deviceaccording to the seventh embodiment of the present invention;

[0119]FIG. 37 is a sectional view showing a projection of an MVA liquidcrystal display device according to an eighth embodiment of the presentinvention;

[0120]FIG. 38 is a sectional view showing a substrate and a mask toexplain a method of manufacturing the MVA liquid crystal display deviceaccording to the eighth embodiment of the present invention;

[0121]FIG. 39A is a sectional view showing a liquid crystal displaydevice according to a ninth embodiment of the present invention, andFIG. 39B is a plan view showing a liquid crystal layer to show tiltdirections of liquid crystal molecules;

[0122]FIG. 40 is a sectional view showing a liquid crystal displaydevice according to a tenth embodiment of the present invention;

[0123]FIG. 41A is a sectional view showing a liquid crystal displaydevice according to an eleventh embodiment of the present invention, andFIG. 41B is a plan view showing liquid crystal layers to show tiltdirections of liquid crystal molecules;

[0124]FIG. 42 is a sectional view showing a liquid crystal displaydevice according to a twelfth embodiment of the present invention;

[0125]FIG. 43 is a plan view showing the liquid crystal display deviceaccording to the twelfth embodiment of the present invention;

[0126]FIG. 44 is a plan view showing a liquid crystal display deviceaccording to a thirteenth embodiment of the present invention;

[0127]FIGS. 45A and 45B are plan views showing alignment states of theliquid crystal molecules in a liquid crystal display device according toa fourteenth embodiment of the present invention;

[0128]FIG. 46 is a plan view showing the alignment state of the liquidcrystal molecules in a liquid crystal display device according to afifteenth embodiment of the present invention;

[0129]FIG. 47 is a plan view showing one pixel of an MVA liquid crystaldisplay device according to a sixteenth embodiment of the presentinvention;

[0130]FIG. 48 is a sectional view showing a sectional shape at aposition of a XI-XI line in FIG. 47;

[0131]FIG. 49 is a view #1 showing an effect in the sixteenth embodimentof the present invention, wherein an alignment state of the liquidcrystal molecules is shown when auxiliary projections are arranged atpredetermined positions;

[0132]FIG. 50 is a view #2 showing an effect in the sixteenth embodimentof the present invention, wherein a state in which alignment failure ofthe liquid crystal molecules is generated is shown when the auxiliaryprojections are arranged at positions deviated from the predeterminedpositions;

[0133]FIG. 51 is a view #3 showing an effect in the sixteenth embodimentof the present invention, wherein a state in which no alignment failureof the liquid crystal molecules is generated because of a pre-tilt anglerevealing process is shown even when the auxiliary projections arearranged at the positions deviated from the predetermined positions;

[0134]FIG. 52 is a plan view showing a liquid crystal display deviceaccording to a seventeenth embodiment of the present invention;

[0135]FIG. 53 is a plan view showing a liquid crystal display deviceaccording to an eighteenth embodiment of the present invention;

[0136]FIG. 54 is a schematic sectional view showing the liquid crystaldisplay device according to the eighteenth embodiment of the presentinvention;

[0137]FIG. 55 is a view showing equipotential lines when a voltage isapplied between a pixel electrode and a common electrode, in theeighteenth embodiment of the present invention;

[0138]FIG. 56 is a graph showing a result to check whether or notdisclination is generated after a dielectric film is formed by using twotype dielectric materials;

[0139]FIG. 57 is a view showing a problem caused when high dielectricportions are arranged in the center between slit rows and low dielectricportions are arranged at portions opposing to the slits;

[0140]FIGS. 58A and 58B are views showing a variation #1 of theeighteenth embodiment of the present invention; and

[0141]FIG. 59 is a view showing a variation #2 of the eighteenthembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0142] Embodiments of the present invention will be explained in detailwith reference to the accompanying drawings hereinafter.

[0143] First Embodiment

[0144]FIG. 15 shows a planar state of a TFT substrate of one pixel of anMVA mode liquid crystal display device according to a first embodimentof the present invention, except for an insulating film and dielectricprojections. FIG. 16 is a plan view showing the state in which adielectric structure is formed on the TFT substrate shown in FIG. 15.FIG. 17 is a sectional view taken along a II-II line in FIG. 16. FIG. 18is a sectional view taken along a III-III line in FIG. 16. FIG. 19 is asectional view taken along a IV-IV line in FIG. 16.

[0145] In FIG. 15, a plurality of gate bus lines 2 that extend in the Xdirection (lateral direction in FIG. 15) are formed at a distance in theY direction (longitudinal direction in FIG. 15) on a first glasssubstrate (TFT substrate) 1 on which TFTs are formed.

[0146] A capacitive bus line (storage capacitance forming electrode) 3extending in the X direction is formed between the gate bus lines 2.Auxiliary capacitive branch lines 3 a that have a length not to touchthe gate bus lines 2 are formed from the capacitive bus line 3 in the Ydirection so as to oppose to a part of drain bus lines, described later.

[0147] The gate bus lines 2, the capacitive bus lines 3, and theauxiliary capacitive branch lines 3 a are formed simultaneously.

[0148] In other words, the gate bus lines 2, the capacitive bus lines 3,and the auxiliary capacitive branch lines 3 a are formed by forming analuminum film of 100 nm thickness and a titanium film of 50 nm thicknesson the first glass substrate 1 by the sputtering and then patterningthese films by the photolithography method. The reactive ion etching(RIE) method using a mixed gas of BCl₃ and Cl₂ is employed in thepatterning.

[0149] As shown in FIG. 17, the gate bus line 2 and the capacitive busline 3 is covered with a gate insulating film 4 formed of siliconnitride that is formed by the plasma-enhanced chemical vapor deposition(PE-CVD) method to have a thickness of 400 nm. A plurality of drain buslines 5 extending in the Y direction are formed on the gate insulatingfilm 4 in the X direction at a distance.

[0150] A TFT (thin film transistor) 6 is formed as the active element inthe neighborhood of an intersection point between the gate bus line 2and the drain bus line 5.

[0151] As shown in FIG. 18, the TFT 6 has an active layer 6 a formed viathe gate insulating film 4 in a region to cross a part of the gate busline 2, a drain electrode 6 d formed on the active layer 6 a on one sideof the gate bus line 2, and a source electrode 6 s formed on the activelayer 6 a on the other side of the gate bus line 2. The drain electrode6 d is connected to the adjacent drain bus line 5.

[0152] The drain electrode 6 d and the source electrode 6 s areseparated on a channel protection film 6 b foninecl on a channel regionof the active layer 6 a.

[0153] The channel protection film 6 b is formed by the followingmethod.

[0154] In other words, a silicon nitride film of 140 nm thickness isformed on the active layer 6 a and the gate insulating film 4 by thePE-CVD method, and then photoresist (photosensitive resin) is coated onthe silicon nitride film. Then, a resist pattern is formed by exposingand developing the photoresist. The exposure process has a firstexposure step of irradiating the exposure light onto the photoresistfrom the lower surface of the glass substrate 1 by using the gate busline 2 as an exposure mask and a second exposure step of irradiating theexposure light onto the photoresist from the upper surface of the glasssubstrate 1 by using the normal exposure mask. Accordingly, edges of theresist pattern are defined by edges of the gate bus line 2. Then, thechannel protection film 6 b made of the silicon nitride film is formedby etching the silicon nitride film in the region, that is not coveredwith such resist pattern, by the wet method using the bufferhydrofluoric acid or the RIE method the hydrofluoric acid group gas.

[0155] In this case, the active layer 6 a is formed by patterning aundoped amorphous silicon film that is formed on the gate insulatingfilm 4 by the PE-CVD method to have a thickness of 30 nm.

[0156] Also, all the source electrode 6 s, the drain electrode 6 d, andthe drain bus line 5 are formed by forming an n+-type amorphous siliconfilm of 30 nm thickness, a titanium film of 20 nm thickness, an aluminumfilm of 75 nm thickness, and a titanium film of 80 nm thickness insequence on the gate insulating film 4 and the channel protection film 6b and then patterning these films by using as a sheet of mask. Thisetching is carried out by the RIE method using a mixed gas of BCl₃ andCl₂. The channel protection film 6 b acts as an etching stopper in thisetching.

[0157] The TFT 6 and the drain bus line 5 are covered with a protectioninsulating film 7 formed of silicon oxide or silicon nitride.

[0158] Also, a transparent pixel electrode 8 made of ITO having athickness of 70 nm is formed on the protection insulating film 7 in aregion surrounded by two drain bus lines 5 and two gate bus lines 2. Thepatterning of the ITO film is carried out by the wet etching methodusing oxalic acid group etchant.

[0159] The pixel electrode 8 is electrically connected to the sourceelectrode 6 s through a hole 7 a in the protection insulating film 7.

[0160] Insulating projections 10 having zig-zag bending patternsextending in the Y direction are formed on the protection insulatingfilm 7 and the pixel electrode 8 at a distance in positions indicated bya chain double-dashed line shown in FIG. 15. A bending angle of thezig-zag bending patterns is roughly 90 degrees, and its bending point isarranged in the almost center of the gate bus line 2. Side surfaces ofthe projection 10 are inclined to the substrate surface.

[0161] Also, as shown in FIG. 16 to FIG. 19, dielectric structures 11are formed on the protection insulating film 7 to be interposed betweenthe gate bus line 2, the drain bus line 5, and the pixel electrode 8respectively.

[0162] The dielectric structure 11 and the projection 10 are formed bythe following method, for example.

[0163] In other words, high-sensitivity negative type resist andlow-sensitivity negative type resist are coated in sequence on theprotection insulating film 7 and the pixel electrode 8. Then, latentimages of the bending patterns are formed on the high-sensitivitynegative type resist by the first exposure. In the first exposure,luminous exposure is set not to expose the low-sensitivity negative typeresist. Then, latent inages are formed by irradiating the exposure lightonto regions of the low-sensitivity negative type resist on the gate busline 2 and the drain bus line 5 and their peripheral portions. Forexample, the exposure light is irradiated at least onto an area extendedfrom the gate bus line 2 to an edge of the pixel electrode 8 and an areaextended from the drain bus line 5 to an edge of the pixel electrode 8in one pixel area. The high-sensitivity negative type resist is exposedat the same pattern simultaneously with the exposure of thelow-sensitivity negative type resist. In this case, it is possible tosay that the resists having different sensitivities are substantiallythe same dielectric material.

[0164] After this, if the patterns are formed by developingsimultaneously the low-sensitivity negative type resist and thehigh-sensitivity negative type resist, the L-shaped dielectricstructures 11 shown in FIG. 16 and the projections 10 having the bendingpatterns are formed integrally. In this case, since th projections 10 isformed of the high-sensitivity negative type resist while the dielectricstructures 11 are formed of both the low-sensitivity negative typeresist and the high-sensitivity negative type resist, the dielectricstructures 11 become thicker than the projections 10.

[0165] In the above example, the dielectric structure 11 and theprojection 10 are formed to have different heights. Since only one layerof the above photosensitive resist is needed if they have the sameheight, the above structures can be implemented by the same process asthe prior art. For example, a film thickness of the dielectric structure11 and the projection 10 is set to more than 1 μm.

[0166] Such projection 10 and the dielectric structure 11 as well as thepixel electrode 8 and the protection insulating film 7 are covered withthe alignment film (vertical alignment film) 9 formed of resin.

[0167] Next, the opposing substrate that opposes to the first glasssubstrate 1 will be explained hereunder.

[0168] The opposing substrate consists of the second glass substrate 12shown in FIG. 17, and then a red (R), green (G), blue (B) color filterfilm 13 is formed on the opposing substrate. Also, a black matrix 14that has a pattern to oppose to the gate bus line 2, the drain bus line5, and the capacitive bus lines 3 is formed on the color filter film 13.In addition, a transparent common electrode 15 made of ITO is formed onthe color filter film 13 to cover the black matrix 14.

[0169] Projections 16 having zig-zag bending patterns are formed on thecommon electrode 15. As indicated by a chain double-dashed line in FIG.15, the projections 16 are arranged on the first glass substrate 1 atpositions in the almost middle between a plurality of projections 10.

[0170] The projections 10 on the first glass substrate 1 side and theprojections 16 on the second glass substrate 12 side intersect withedges of the pixel electrodes 8 respectively by an angle of 45 degrees.

[0171] In addition, an alignment film (vertical alignment film) 17 forcovering the projections 16 is formed on the common electrode 15.

[0172] The first glass substrate 1 and the second glass substrate 12,formed as above, are stuck to each other at a predetermined distance todirect the alignment films 9, 17 inward. Then, liquid crystal material18 having negative dielectric anisotropy is filled into a space betweenthe alignment films 9, 17. The liquid crystal molecules in the liquidcrystal material 18 are aligned perpendicularly to the substrate surfaceunder the condition that no voltage is applied between the commonelectrode 15 and the pixel electrode 8. Also, the liquid crystalmolecules are tilted in the direction orthogonal to straight portions ofthe patterns of the projections 10, 16 under the condition that theintermediate voltage is applied between the common electrode 15 and thepixel electrode 8.

[0173] In this case, it is desired that the projections 10, 16 areformed of material having the dielectric constant equivalent to or lessthan the relative dielectric constant of the liquid crystal material 18.

[0174] A first polarizing plate 21 is arranged on an outer surface ofthe first glass substrate 1, and a second polarizing plate 22 isarranged on an outer surface of the second glass substrate 12. Anarrangement of the first polarizing plate 21 and the second polarizingplate 22 is cross-nicol. When the substrate is viewed vertically,polarization axes of the first polarizing plate 21 and the secondpolarizing plate 22 intersect with straight portions of the patterns ofthe projections 10, 16 by an angle of 45 degrees.

[0175] In the first embodiment, the structure is formed in whichrespective spaces between the pixel electrode 8, the gate bus line 2,and the drain bus line 5 are covered with the dielectric structure 11.Accordingly, a gap between the alignment film 9 on the gate bus line 2and the alignment film 17 on the common electrode 15 becomes narrow, andthus a defining force of the alignment films against the liquid crystalmolecules can be enhanced. In addition, a voltage drop is generatedbetween the gate bus line 2 and the common electrode 15 by thedielectric structure, and also the voltage applied to the liquid crystallayer is lowered.

[0176] As results of them, as shown in FIGS. 20A and 20B, the liquidcrystal molecules L over the gate bus line 2 are difficult to tilt sincethey receive the strong vertical alignment definition by the alignmentfilms 9, 17. Accordingly, the alignment direction of the liquid crystalmolecules L is hardly affected by the variation of the surroundingelectric field, and thus the variation of the stray capacitance can bereduced.

[0177] Also, the relative dielectric constant of the dielectricstructure 11 is not varied and constant such as about 2 to 5, and issmaller than the relative dielectric constant of the liquid crystal inmany cases. For example, the dielectric structure 11 having the relativedielectric constant of 3.2 is used. The liquid crystal for the MVA modehas ε (dielectric constant in the perpendicular direction to the liquidcrystal molecules)=3.6, ε//(dielectric constant in the paralleldirection to the liquid crystal molecules)=8.4.

[0178] Accordingly, as shown in FIG. 20A and FIG. 20B, the capacitanceCgc between the pixel electrode 8 and the gate bus line 2 and thecapacitance Cds between the pixel electrode 8 and the drain bus line 5are seldom changed. Further, because the voltage drop is gen rated bythe dielectric structure 11, the voltage applied to the liquid crystallayer on the gate bus line 2 is also lowered. As a result, the straycapacitances between the bus lines can be reduced and the straycapacitance between the bus line and pixel electrode can be reduced.

[0179] With the above, since the variation of the stray capacitancesbecomes extremely small and the constant pixel potential can be alwaysobtained, the aperture ratio can be increased by reducing the width ofthe capacitive bus line 3. In addition, when the potential of the pixelelectrode is kept constant, generation of the flicker can be prevented.

[0180] For example, in the liquid crystal display panel employing theabove structure, the variation of the common voltage is less than 10 mVand also the flicker rate can be improved below 3%, which is reducedbelow a half of the flicker rate in the prior art. Accordingly, yield ofthe liquid crystal display panel can be improved.

[0181] In the above first embodiment, since formation of the dielectricstructures 11 and formation of the projections 10 can be performed bythe same step, the above liquid crystal display device can be formed tohardly increase the number of processes rather than the prior art.

[0182] In this case, the above dielectric structure 11 may be formed toprotrude to such extent that it overlaps slightly with the pixelelectrode 8.

[0183] Second Embodiment

[0184] In the first embodiment, only spaces between the gate bus lines 2and the drain bus lines 5 for driving the pixel electrodes and the pixelelectrodes 8 are covered with the dielectric structures 11 in one pixelarea.

[0185] Arrangement areas of the dielectric structures are not limited tothe above. For example, as shown in FIG. 21, dielectric structures 11 amay be provided between neighboring pixel electrodes 8. In suchstructure, a peripheral area of the pixel electrode 8 and the gate busline 2 and the drain bus line 5 are covered with the dielectricstructure 11 a.

[0186] The flicker rate can be improved by employing such structurerather than the first embodiment.

[0187] Further, only spaces between the gate bus line 2 and the pixelelectrode 8 may be covered with the dielectric structure, or only spacesbetween the drain bus line 5 and the pixel electrode 8 may be coveredwith the dielectric structure. According to these structures, the effectby the dielectric structures 11, 11 a shown in FIG. 16 or FIG. 21 cannotbe achieved, but both the common voltage variation and the flicker rateare good.

[0188] Furthermore, in FIG. 15, the dielectric structure may be formedonly in intersecting areas of the gate bus lines 2 and the projections11 and their neighboring areas. Otherwise, the dielectric structure maybe formed only in intersecting areas of the drain bus lines 5 and theprojections 11 and their neighboring areas. According to thesestructures, such effects can be derived that the influence of the chargeof the projections 10 can be reduced rather than the first embodimentand also the alignment change between the gate bus lines 2 and the pixelelectrodes 8 in the neighborhood of the projections 10 can besuppressed. In this case, the flicker rate cannot be so improved incontrast to the dielectric structures shown in FIG. 16 or FIG. 21, butboth the common voltage variation and the flicker rate are good.

[0189] The above descriptions are all directed to the embodiments inwhich the dielectric structures are formed on the first glass substrate1 side, but the dielectric structures may be formed on the second glasssubstrate (opposing substrate) 12 side. For example, as shown in FIG.22, such a structure may be employed that dielectric structures 11 b areformed on the common electrodes 15 at positions to which the dielectricstructures 11, 11 a shown in FIG. 16 or FIG. 21 oppose, and then thealignment film 17 is formed thereon. In this case, an effect for fixingperfectly the capacitance Cgs between the gate and the pixel electrodeand the capacitance Cds between the drain and the pixel electrode cannotbe achieved, but an effect for suppressing the alignment change to thelowest minimum can be expected by the narrower cell gap effect. Suchnarrower cell gap effect remarkably appears by setting a thickness ofthe dielectric structure 1 b to more than 1 μm, like the firstembodiment.

[0190] Also, in the above examples, the dielectric structure is formedonly by the resist, for example. In addition to this, as shown in FIG.23, overlapped portions may be utilized as a part of the dielectricstructure on the opposing substrate side by overlapping red, green, bluecolor filters 13R, 13G, 13B mutually on the boundary portions betweenthe pixel areas respectively. Accordingly, the liquid crystal can beremoved from the areas in which the alignment change is suppressed inthe area other than the pixel electrodes 8, and thus change in thecapacitance due to the alignment change is not generated. As a result,the similar effect to the first embodiment can be achieved.

[0191] As the areas in which the differently-colored color filters 13R,13G, 13B are overlapped with each other, only the areas between the gatebus lines 2 and the pixel electrodes 8 or the areas between the drainbus lines 5 and the pixel electrodes 8 may be considered. In this case,the dielectric structure may be formed on the first glass substrate 1 soas to oppose to the overlapped portions of the differently-colored colorfilters 13R, 13G, 13B.

[0192] As shown in FIG. 23, a dielectric structure 11 c may be formed onthe overlapped portions of the red, green, blue color filters 13R, 13G,13B, or may be omitted. However, in the case that the structure shown inFIG. 23 is employed, spacers (spherical or cylindrical spacers)interposed between the substrates can be omitted if the overlappedportions of the color filters 13R, 13G, 13B and the dielectricstructures 11 c formed thereon are employed as struts to maintain thecell gap.

[0193] In this case, the above dielectric structures may be formed onboth the second glass substrate 12 side and the first glass substrate 1side. Then, the cell gap may be maintained by the vertically-engageddielectric structures. In addition, the variation of the common voltageof less than 10 mV and the flicker rate of less than 2% can be achievedby employing the optimum structure.

[0194] The structure in which at least one of the projection 10 on thefirst glass substrate 1 side and the projection 16 on the second glasssubstrate 12 side is not provided in the neighborhood of the areaintersecting with the gate bus line 2, the structure in which at leastone of them is not provided in the neighborhood of the area intersectingwith the drain bus line 5, or the structure in which at least one ofthem is not provided in areas other than the pixel electrode 8 may beemployed.

[0195] In the first embodiment and the second embodiment, theprojections are employed as the means for defining the alignmentdirection of the liquid crystals. The slits may be formed on at leastone of the pixel electrode and the common electrode in place of theprojections.

[0196] The dielectric structure shown in the first embodiment and thesecond embodiment may be applied to not only the MVA mode liquid crystaldisplay device but also other liquid crystal display devices. In thiscase, the slits formed in the pixel electrode 8 or the common electrode15 may be used instead of either one of the projections 10 on the firstglass substrate 1 side and the projections 16 on the second glasssubstrate 12 side.

[0197] As described above, according to the present invention, since thedielectric structures are arranged in the areas between the gate buslines (first bus lines) and the pixel electrodes, both intersect witheach other, or the areas between the drain bus lines (second bus lines)and the pixel electrodes, variation of the stray capacitance betweenthem can be suppressed by fixing the dielectric constant between thepixel electrodes and the bus lines by the dielectric structures. Also,since the dielectric structures are also formed on the bus lines, thethickness of the liquid crystal layer in the dielectric structures canbe reduced. As a result, the liquid crystal molecules in the liquidcrystal layer is hardly moved from the vertical alignment and thus thevariation of the stray capacitance can be extremely reduced. Besides,since a component of the stray capacitance over the bus lines fixed bythe dielectric structures is increased, the variation of the straycapacitance can be reduced.

[0198] As mentioned above, since the pixel potential becomes constant bysuppressing the variation of the stray capacitance, generation of theflicker can be prevented. In addition, the aperture ratio can beenhanced by reducing the width of the capacitive bus line to suppressthe variation of the capacitance.

[0199] Third Embodiment

[0200]FIG. 24 is a sectional view showing a third embodiment of thepresent invention, that has the similar structure to the firstembodiment other than the pixel electrode, the projection, and thedielectric structure. In FIG. 24, same references as those in FIG. 17denote same elements.

[0201] In FIG. 24, the gate bus line 2 and the capacitive bus line 3 areformed on the first glass substrate (TFT substrate) 1. Also, like thefirst embodiment, the drain bus line 5 and the thin film transistor(TFT) 6 are formed on the gate insulating film 4 that covers these buslines 2, 3. The drain bus line 5 and the thin film transistor (TFT) 6are covered with the protection insulating film 7, and then a pixelelectrode 30 is formed on the protection insulating film 7. As shown inFIG. 25, the pixel electrode 30 is arranged in an area that issurrounded by the gate bus line 2 and the drain bus line 5.

[0202] Slits 30 a, 30 b that extend like the V-shape from edge areas ofthe pixel electrode 30 existing on the capacitive bus line 3 arc formedin the pixel electrode 30. Slits 30 c, 30 d are formed in parallel withthe slits 30 a, 30 b in the pixel electrode 30. The slit width is 10 μm,for example.

[0203] These slits (domain defining means) 30 a to 30 d divide the pixelelectrode 30 into five areas. These areas are electrically connectedmutually by connecting portions 30 n that separate the slits 30 a to 30d into plural areas.

[0204] In addition, connecting portions 30 e used to connectelectrically five areas divided by the slits 30 a to 30 d are formedwithin a predetermined width w1, e.g., within a range of 4 μm, from theedge of the pixel electrode 30. End portions of the slits 30 a to 30 dare separated by the connecting portions 30 e.

[0205] The connecting portions 30 e acts as an alignment controllingmeans for forming an alignment singular point of s=−1. As shown in FIGS.26A and 26B, according to the alignment controlling means having thealignment singular point of s=−1, the liquid crystal molecules L in onedirection out of two orthogonally intersecting directions around a pointO are aligned to direct to the point O while the liquid crystalmolecules L in the other direction are aligned to direct to the oppositeside to the point O. Also, the liquid crystal molecules L inclined tothese directions by 45 degrees are directed to different directionsrespectively.

[0206] In this case, as shown in FIG. 26B, according to the alignmentcontrolling means forming an alignment singular point of s=+1 describedin following embodiments, all liquid crystal molecules L around thepoint O are aligned to direct to the point O.

[0207] As shown in FIG. 24, the above-mentioned pixel electrode 30 isconnected to the TFT 6 and is covered with the alignment film 9.

[0208] Like the first embodiment, as shown in FIG. 24, the color filter13, the black matrix 14, the common electrode 15, dielectric projections(domain defining means) 31, and the alignment film 17 are formed insequence on the surface of the second glass substrate (opposingsubstrate) that is arranged to oppose to the pixel electrode 30.

[0209] As the alignment films 9, 17 on the first and second glasssubstrates 1, 12, JALS-684 (product name manufactured by JSR Inc.), forexample, is employed.

[0210] Like the first embodiment, as indicated by a chain double-dashedline in FIG. 25, the dielectric projections 31 are formed in a zig-zagfashion to oppose to positions that pass through between the slits 30 ato 30 d of the pixel electrode 30. The projections 31 are formed byphotosensitive acrylic resin PC-335 (product name manufactured by JSRInc.), for example. Patterns of the projections 31 are formed by coatingthe photosensitive acrylic resin on the substrate by virtue of spincoating, then baking the resin at 90° C. for 20 minutes, thenirradiating selectively the ultraviolet rays by using a photo mask, thendeveloping the resin by an organic alkaline liquid developer (TMAHO, 2wt %), and then baking the resin at 200° C. for 60 minutes. A width ofthe projection 31 is 10 μm and a height of the projection 31 is 1.5 μm.

[0211] A liquid crystal panel is formed by sticking the first glasssubstrate 1 and the second glass substrate 12 having the above structuretogether and then injecting the liquid crystal into a space betweenthem. In this case, MJ961213 (product name manufactured by Merck Inc.)is employed as the liquid crystal material.

[0212] In the liquid crystal display device having the aboveconfiguration, the slits 30 a to 30 d of the pixel electrode 30 actingas the domain defining means are not formed at the edges of the pixelelectrode 30 and its neighboring area, and the alignment singular pointsare formed there. Accordingly, difference of the domain states betweenthe white monitored when the display of the pixel is changed from theblack to the white and the white monitored when the display of the pixelis changed from the half tone to the white can be reduced to anunobtrusive level, so that the domain change can be reduced up to aundistinguishable level as the residual image.

[0213] Here, the domain defining means of the liquid crystal moleculesis not limited to the linear slits in the pixel electrode. For example,the structure may be employed in which the linear dielectric projectionslike the first embodiment are provided in place of the slits on thepixel electrode. In this case, if the separated portions that are notintersected with the edges of the pixel electrode are formed as theprojections, the alignment singular point of s=−1 is formed at the edgeportion of the pixel electrode on the prolonged line of the projection.

[0214] Also, in place of forming the projections 31 on the commonelectrode 15 being formed on the opposing substrate 12 side, the slitsmay be formed in the common electrode 15.

[0215] Fourth Embodiment

[0216] In the third embodiment, the alignment singular point of s=−1 isformed at the intersecting portions between the structures or the slitsformed on the pixel electrode and the edges of the pixel electrode. Incontrast, in a fourth embodiment, such a configuration will be explainedhereunder that the alignment singular point of s=+1 is formed at theintersecting portions between the structures or the slits formed on thesubstrate opposing to the substrate having the pixel electrode and theedges of the pixel electrode.

[0217]FIG. 27 is a plan view showing the pixel area of the liquidcrystal display device according to the fourth embodiment of the presentinvention. FIG. 28 is a sectional view taken along a VII-VII line inFIG. 27.

[0218] In FIG. 27, slits 33 a, 33 b that extend like the V-shape fromthe edge areas of the pixel electrode 33 existing on the capacitive busline 3 are formed in the pixel electrode 33. Slits 33 c, 33 d are formedin parallel with these slits 33 a, 33 b in the area of the pixelelectrode 33 near the gate bus line 2. The slit width is 10 μm, forexample. The slits 33 a to 33 d are also formed on the edges of thepixel electrode 33. The slits 33 a to 33 d are separated by theconnecting portions 33 e.

[0219] Also, as shown in FIG. 27 and FIG. 28, in the dielectricprojections (structures) 34 formed on the opposing substrate 12 side,the alignment singular point in the neighborhood of the edge of thepixel electrode 33 is formed as s=+1 by setting a portion 34 a opposingto the edge of the pixel electrode 33 higher than other areas. A heightof the portion of the projection 34 to oppose to the edge of the pixelelectrode 33 is set to 2.5 μm, and a height of other portion is set to1.5 μm.

[0220] The projections 34 are formed of the same constituent material asthe projections 31 in the third embodiment. First, the pattern of theprojections 34 are formed on the common electrode 15 to have a height of1.5 μm, and then projections 34 a of 1.0 μm height is selectivelystacked in areas opposing to the edges of the pixel electrode 33.

[0221] In this manner, since a portion of the projection 34 on theopposing substrate 12 side, that opposes to the edge of the pixelelectrode 33, is set higher than other portions, the alignment singularpoint of s=+1 is formed on the edge of the pixel electrode 33, as shownin FIG. 27 and FIG. 28. As a result, the influence of the alignment ofthe liquid crystal molecules L at the edge of the pixel electrode 33upon the liquid crystal molecules at the inside of the pixel electrode33 can be prevented by the alignment singular point, so that generationof the residual images caused when the display is changed from the halftone display to the white display can be prevented.

[0222] In the case that the slits are formed in the common electrode 15on the opposing substrate 12 in place of the projections 34, the similaroperation and effect can be achieved if such slits are divided atportions opposing to the pixel electrode 33.

[0223] By the way, a combination of the TFT substrate in the thirdembodiment and the opposing substrate in the fourth embodiment canprovide the best structure. More particularly, the preferable structurecan be obtained by separating the linear slits or the linear projectionsformed on the TFT substrate side not to intersect with the edge of thepixel electrode and also separating the linear slits in the commonelectrode on the common electrode side not to intersect with the pixelelectrode or forming portions of the linear projections, that oppose tothe edge of the pixel electrode, on the common electrode side thickerthan other portions.

[0224] Fifth Embodiment

[0225] In the third embodiment, bending portions of the slits formed onthe pixel electrode, i.e., intersecting portions of prolonged lines ofthe slits in two directions are formed to coincide with the edge of thepixel electrode. In this case, such intersection points may be shiftedinward from the edge of the pixel electrode.

[0226]FIG. 29 is a plan view showing a pixel electrode and itsneighboring area of a liquid crystal display device according to a fifthembodiment of the present invention.

[0227] In FIG. 29, a bending portion 35 b of a slit 35 a opened in thepixel electrode 35 is formed to retreat inward from the edge of a pixelelectrode 35. For example, a distance from the bending portion 35 b tothe edge of the pixel electrode 35 is set to 4 μm and a width of theslit 35 a is set to 10 μm.

[0228] Also, like the first embodiment, projections 36 are formed on theopposing substrate 12 side at positions passing through between theslits 35 a.

[0229] According to this, the influence of the electric field by theedge of the pixel electrode 35 upon the bending portion 35 b of the slit35 a can be reduced and thus generation of the residual images can besuppressed.

[0230] In FIG. 29, the structure in which the slits are formed in thepixel electrode 35 is employed. In the event that the dielectricprojections are formed on the pixel electrode 35 instead of the slitslike the first embodiment, the influence of the electric field by theedge of the pixel electrode 35 upon the bending portion of theprojections can be reduced and thus generation of the residual imagescan be suppressed if the bending portions of the projections are formedto retreat inward from the edge of the pixel electrode.

[0231] Also, as shown in FIG. 30, for example, as the shape of adielectric projection 37 formed as the alignment controlling means onthe opposing substrate 12, if the projection 37 is bent in the areaopposing to the pixel electrode such that the bending portion isarranged to be shifted inward from the edge of a pixel electrode 38, theinfluence of the electric field by the edge of the pixel electrode 38upon the bending portion can be reduced and thus the residual imagesuppressing effect can be achieved. In this case, for example, a widthof the projection 37 is set to 10 μm and a distance from the bendingportion to the edge of the pixel electrode 38 is set to 4 μm.

[0232] It may be considered that the slits are formed in the commonelectrode 15 shown in FIG. 24 as the alignment controlling means on theopposing substrate 12 in place of the dielectric projections 37.However, since normally the color filter 13 is formed under the commonelectrode 15, it is not preferable from aspects of precision andreliability to form the slit in the common electrode 15.

[0233] In FIG. 30, because the bending portions (intersecting portions)of the slits 38 a, 38 b formed on the pixel electrode 38 to extend intwo directions are positioned on the outside of the pixel electrode 38,the influence of the electric field by the edge of the pixel electrode38 upon the bending portions can be eliminated. Accordingly, generationof the alignment state that is different from the essential alignmentcontrol and generated by the projections or the slits can be reduced,and also the residual images caused when the display is changed from thehalf tone display to the white display can be eliminated.

[0234] Sixth Embodiment

[0235]FIG. 31A is a plan view showing a pixel electrode and itsneighboring area of a liquid crystal display device according to a sixthembodiment of the present invention.

[0236] In FIG. 31A, such a structure is employed that intersectingportions of a first slit 40 a and a second slit 40 b, that are formedlike a V-shape near the center of a pixel electrode 40, are connectedvia a slit 40 e, that is formed in parallel with the edge of the pixelelectrode 40, at a position inner than the edge. A distance of aclearance 40 g between the slit 40 e and the edge of the pixel electrode40 is set to 4 μm, for example.

[0237] Also, third and fourth slits 40 c, 40 d are formed in the pixelelectrode 40 near the gate electrode 2.

[0238] These first to fourth slits 40 a to 40 d are separated byconnecting portions 40 f at plural portions. Therefore, the pixelelectrode 40 is divided into five areas A to E by the first to fourthslits 40 a to 40 d, and these areas A to E are electrically connected bythe connecting portions 40 f.

[0239] The area C divided by the first and second slits 40 a, 40 b isopposed electrically and structurally to the storage capacitance formingelectrode (capacitive bus line) 3. Also, at least two electricalconnecting paths are opposed electrically to the storage capacitanceforming electrode 3.

[0240] Accordingly, as shown in FIG. 31B, the area B and the area D ofthe pixel electrode 40 are connected via two routes of a route B-C-D anda route B-D. Then, if the area C of the pixel electrode 40 and thestorage capacitance forming electrode 3 are short-circuited, four areasA, B, D, E of the pixel electrode 40 can be electrically connected viathe existing connecting portion 40 f and the clearance 40 g bydisconnecting the electrical connections of B-C and C-D by the laserirradiation onto the connection portion 40 f. Therefore, it is possibleto drive the liquid crystal molecules in most portions other than thearea C.

[0241] Such pixels that can be driven in areas other than such area Chave slightly different display characteristic in contrast to the normalstate in which the area C of the pixel electrode 40 and the storagecapacitance forming electrode 3 are not short-circuited. However, sincesuch different display can be improved up to a level to clear thedisplay defect standard according to the number of defective pixels andthe generation location, the improvement in yield of the TFT substratecan be achieved. This can be attained by such a structure that pluralareas of the pixel electrode divided by the slits are connected the edgeportion of the pixel electrode, whereby this respect is different fromthe structure in the prior art.

[0242] In this case, if the pixel electrode 40 is divided into at leastthree areas by the first and second slits 40 a, 40 b, for example, suchyield improving effect can be attained.

[0243] Next, change of the domain on the slits when the presentinvention is applied will be explained with reference to FIGS. 32A and32B hereunder.

[0244] First, as shown in FIG. 32A, when the display is changed from theblack display to the white display, the number of domains divided by theconnecting portions on the slit 40 a is eight such as {circle over (1)}to {circle over (8)}. Also, according to FIG. 32A, the domains {circleover (8)} and {circle over (9)} are increased in number rather than theprior art shown in FIG. 10A. This is because the singular point s=−1 ofthe alignment vector is formed at the edge of the pixel electrode.

[0245] Then, as shown in FIG. 32B, when the display is changed from theblack display to the white display via the half tone display, thedomains {circle over (6)} and {circle over (8)} are connected and thusthe domain {circle over (7)} disappears. In other words, the change ofdomains on the slits can be suppressed at a very small level rather thanFIG. 10A in the neighborhood of the edge of the pixel electrode.

[0246] According to the present invention, in the display mode in whichthe liquid crystal molecules alignment is controlled by the structuresor the slits provided on the substrate, the improvement of the responsecharacteristic can be achieved by forming the alignment singular points,at which the liquid crystal molecules become s=−1 or s=+1, on theintersecting portions between the prolonged lines of the structures orthe slits and the pixel electrode, etc.

[0247] Besides, in the present invention, two routes, i.e., the routepassing through the area in which the storage capacitance formingelectrode and the capacitance are formed and the route not passingthrough such area are provided as the electrical connecting paths of thepixel electrode. Therefore, if the electric short-circuit between thestorage capacitance forming electrode and the pixel electrode isgenerated, the area in which the capacitance is formed can bedisconnected electrically from other areas, and thus other areas can beemployed as the area in which the liquid crystal molecules can bedriven. As a result, the improvement in yield of the TFT substratemanufacture can be achieved.

[0248] Seventh Embodiment

[0249] Next, a liquid crystal display device according to a seventhembodiment of the present invention will be explained with reference toFIG. 33 to FIG. 36 hereunder.

[0250]FIG. 33 is a plan view showing an MVA liquid crystal displaydevice according to the seventh embodiment. A plurality of gate buslines 205 are formed to extend along the row direction (lateraldirection) in FIG. 33. A capacitive bus line 208 extending in the rowdirection is arranged between two neighboring gate bus lines 205. Thegate bus lines 205 and the capacitive bus lines 208 are covered with aninsulating film. A plurality of drain bus lines 207 that extend alongthe column direction (longitudinal direction) in FIG. 33 are arranged onthis insulating film.

[0251] TFTs 210 are provided to correspond to intersecting portionsbetween the gate bus line 205 and the drain bus line 207. A drain regionof the TFT 210 is connected to the corresponding drain bus line 207. Thegate bus line 205 is also used as a gate electrode of the correspondingTFT 210.

[0252] The drain bus lines 207 and the TFTs 210 are covered with aninterlayer insulating film. A pixel electrode 212 is arranged in an areasurrounded by two gate bus lines 205 and two drain bus lines 207. Thepixel electrode 212 is connected to a source region of the correspondingTFT 210.

[0253] Auxiliary capacitive branch lines 209 branched from thecapacitive bus lines 208 extend along the edge of the pixel electrode212. The capacitive bus lines 208 and the auxiliary capacitive branchlines 209 constitute an auxiliary capacitance between the pixelelectrodes 212. The potential of the capacitive bus lines 208 is fixedat any potential.

[0254] When the potential of the drain bus line 207 is varied, thepotential of the pixel electrode 212 is also varied by the capacitivecoupling due to the stray capacitance. In the configuration in FIG. 33,since the pixel electrode 212 is connected to the capacitive bus lines208 via the auxiliary capacitance, variation in the potential of thepixel electrode 212 can be reduced.

[0255] TFT substrate side projections 217 and CF substrate sideprojections 218 are formed on the opposing surfaces of the TFT substrateand the opposing substrate (the opposing substrate is called a colorfilter (CF) substrate in some cases since normally the color filter isprovided on the opposing substrate side) along zig-zag patternsextending along the column direction respectively. The TFT substrateside projections 217 are arranged at an equal distance in the rowdirection, and bending points are positioned on the gate bus line 205and the capacitive bus lines 208. The CF substrate side projection 218has an almost congruent pattern to the TFT substrate side projection 217and is arranged in the almost middle of two neighboring TFT substrateside projections 217. The projections 217 and 218 have a width of about10 μm respectively.

[0256] The polarizing plates are arranged on both sides of the liquidcrystal cell. The polarizing plates are cross-nicol-arranged such thattheir polarization axes intersect with straight portions of theprojections 217, 218 by an angle of 45 degrees.

[0257]FIG. 34 is a sectional view showing the TFT portion taken along aVIII-VIII line in FIG. 33, and FIG .35 is a sectional view showing thepixel electrode portion taken along a IX-IX dot-dash line in FIG. 33.The TFT substrate 235 and the opposing substrate 236 are arranged inparallel at a distance. Liquid crystal material 229 is filled betweenthe TFT substrate 235 and the opposing substrate 236. The liquid crystalmolecules in the liquid crystal material 229 have the negativedielectric anisotropy.

[0258] As shown in FIG. 34, the gate bus lines 205 are formed on theopposing surface of the glass substrate 201. The gate bus lines 205 areformed by depositing an Al film of 100 nm thickness and a Ti film of 50nm thickness by virtue of the sputtering and then patterning these twolayers. The etching of the Al film and the Ti film is carried out by theRIE using a mixed gas of BCl₃ and Cl₂.

[0259] A gate insulating film 240 is formed on the glass substrate 201to cover the gate bus lines 205. The gate insulating film 240 is formedof an SiN film of 400 nm thickness, and is formed by the PE-CVD method.An active area 241 is arranged on a surface of the gate insulating film240 to cross the gate bus line 205. The active area 241 is formed of anundoped amorphous Si film of 30 nm thickness, and is formed by thePE-CVD method. A surface of the active area 241 over the gate bus lines205 is covered with a channel protection film 242. The channelprotection film 242 is formed of an SiN film of 140 nm thickness. Thechannel protection film 242 is patterned to cover the channel region ofthe TFT 210 in FIG. 33.

[0260] Formation of the channel protection film 242 is carried out bythe following method. First, a surface of the SiN film formed on theoverall surface of the substrate is covered with the photoresist film.An edge of the resist pattern parallel to the row direction in FIG. 33can be defined by exposing the photoresist from a back surface of theglass substrate 201 using the gate bus lines 205 as a photo mask. Anedge of the resist pattern parallel to the column direction in FIG. 33can be defined by exposing the photoresist using the normal photo mask.

[0261] After the photoresist film is developed, the SiN film ispatterned by etching the photoresist film using the buffer hydrofluoricacid etchant. In this case, the SiN film may be patterned by the RIEusing a fluorine group gas. After the SiN film is patterned, the resistpattern is removed. The channel protection film 242 is formed by thesteps performed until now.

[0262] A source electrode 244 and a drain electrode 246 are formed onthe upper surface of the active area 241 on both side areas of thechannel protection film 242 respectively. Both the source electrode 244and the drain electrode 246 have a laminated structure which is formedby laminating an n⁺-type amorphous Si film of 30 nm thickness, a Ti filmof 20 nm thickness, an Al film of 75 nm thickness, and a Ti film of 80nm thickness in sequence. The TFT 210 consists of the gate bus line 205,the gate insulating film 240, the active area 241, the source electrode244 and the drain electrode 246.

[0263] The active area 241, the source electrode 244 and the drainelectrode 246 are patterned by using one etching mask. The etching ofthese films is carried out by the RIE using the mixed gas of BCl₃ andCl₂. At this time, the channel protection film serves as an etchingstopper over the gate bus line 205.

[0264] The pixel electrode 212 is formed on the protection insulatingfilm 248. The pixel electrode 212 is formed of an ITO film of 70 nmthickness, and is connected to the source electrode 244 via a contacthole 250 provided in the protection insulating film 248. Formation ofthe ITO film is performed by the DC magnetron sputtering. The patterningof the ITO film is performed by the wet etching using the oxalic acidgroup etchant. The pixel electrode 212 and the protection insulatingfilm 248 are covered with an alignment film 228.

[0265] Then, a configuration of the opposing substrate 236 will beexplained hereunder. A color filter 251 is formed on the opposingsurface of the glass substrate 227. A light shielding film 252 made ofCr, etc. is formed on a surface of the color filter 251 in an areaopposing to the TFT 210. A common electrode 254 made of ITO is formed onthe surface of the color filter 251 to cover the light shielding film252. A surface of the common electrode 254 is covered with the alignmentfilm 228.

[0266] The pixel electrode portion shown in FIG. 35 will be explainedhereunder. The capacitive bus line 208 is formed on the surface of theglass substrate 201. The capacitive bus line 208 is formed by the samesteps as those applied to the gate bus line 205 shown in FIG. 34. Thegate insulating film 240 and the protection insulating film 248 areformed on the surface of the glass substrate 201 to cover the capacitivebus line 208. The pixel electrode 212 is formed on the surface of theprotection insulating film 248.

[0267] The TFT substrate side projections 217 are formed on the surfaceof the pixel electrode 212. The TFT substrate side projections 217 areformed by coating the polyimide-based photoresist and then patterningthe resist film, as shown in FIG. 33. The surfaces of the TFT substrateside projections 217 and the pixel electrodes 212 are covered with thealignment film 228.

[0268] The color filter 251 is formed on the opposing surface of theglass substrate 227 opposing to the TFT substrate 235. The lightshielding film 252 is formed on a part of the surface of the colorfilter 251. The common electrode 254 is formed on the surface of thecolor filter 251 to cover the light shielding film 252. The CF substrateside projections 218 are formed on the surface of the common electrode254. The CF substrate side projections 218 are formed by the same methodas the formation of the TFT substrate side projections 217. The surfacesof the CF substrate side projections 218 and the common electrode 254are covered with the alignment film 228.

[0269] In order to execute the image display, a constant common voltageis applied to the common electrode 254 and a image signal whose polarityis inverted frame by frame is applied to the pixel electrode 212. If thevoltage applied to the liquid crystal layer when the pixel electrode 212is positive for the common electrode 254 is equal to that applied to theliquid crystal layer when the pixel electrode 212 is negative for thecommon electrode 254, the transmittance obtained when the pixelelectrode 212 has a positive polarity becomes equal to that obtainedwhen the pixel electrode 212 has a negative polarity. Thus, the stabledisplay can be derived.

[0270] Compensating members 221 having the refractive anisotropy areformed on a surface of the glass substrate 201 on the opposite side tothe opposing surface. If viewed along the normal direction of thesubstrate, the compensating members 221 are formed along the edge of theTFT substrate side projections 217 or to overlap substantially withtheir inclined surfaces. The liquid crystal molecules in theneighborhood of the edges of the TFT substrate side projections 217 aretilted against the substrate surface by the influence of the inclinedsurfaces of the projections 217. The tilt has the double refractioneffect on the light transmitted in the thickness direction of the liquidcrystal layer. The compensating members 221 have the refractiveanisotropy to reduce this double refraction effect. Similar compensatingmembers 222 are formed on the surface on the opposite side to theopposing surface so as to correspond to the projections 218.

[0271] In the dark state, the double refraction effect caused by theliquid crystal layer in the neighborhood of the edges of the projections217, 218 is canceled by the double refraction effect caused due to therefractive anisotropy of the compensating members 221 and 222.Therefore, leakage lights in the neighborhood of the edges of theprojections 217, 218 in the dark state can be reduced.

[0272] In order to sufficiently compensate the double refraction effectwhen viewed from the oblique direction, it is preferable that the glasssubstrates 101, 227 should be formed as thin as possible. The case wherethe glass substrate is employed is explained with reference to FIG. 34and FIG. 35. However, even if a thin film substrate of about severaltens μm thickness is employed in place of the glass substrate, thedouble refraction effect can be sufficiently compensated in the obliquedirection.

[0273] Next, a method of manufacturing the compensating members 222shown in FIG. 35 will be explained with reference to FIG. 36 hereunder.A method of manufacturing the compensating members 221 on the TFTsubstrate 235 side is similar to a method explained in the following.

[0274] The transparent electrode layer 260 formed of ITO to have athickness of 100 nm is formed on the surface of the glass substrate 227,that is on the opposite side to the surface on which the projections 218are formed. As shown in FIG. 33, the projection 218 contains locally aportion parallel to the first direction and a portion parallel to thesecond direction perpendicular to the first direction. First, all areasof the surface of the transparent electrode layer 260 are rubbed in thefirst direction.

[0275] Then, the area of the projection 218, in which portions beingparallel to the first direction are aligned, is masked by the resistpattern. Then, areas not covered with the resist pattern are rubbed inthe second direction. After this, the resist pattern is removed. Inother words, the rubbing direction becomes locally parallel to theextending direction of the projections 218.

[0276] A ultraviolet (UV) curable liquid crystal layer 261 of 2.5 μmthickness is formed by coating the material, that is obtained by addingthe photopolymerization initiator of 1 wt % into the UV curable liquidcrystal material, on the surface of the transparent electrode layer 260.As the UV curable liquid crystal material, for example, monoacrylateexpressed by the following chemical formula (1) may be employed.

CH₂═CHCOO—C₆H₄—C₆H₄—C₃H₇  (1

[0277] This monoacrylate exhibits a liquid crystal phase at the roomtemperature. The phase transition temperature Tni of the liquid crystalmaterial is 52° C., the refractive anisotropy Δn of the liquid crystalmaterial is 0.160, and the dielectric anisotropy Δε of the liquidcrystal material is 0.7. The liquid crystal molecules in the UV curableliquid crystal layer 261 are aligned such that their director becomesparallel to the rubbing direction of the transparent electrode layer260.

[0278] A transparent electrode plate 262 is arranged on the UV curableliquid crystal layer 261 to come into contact with its surface. Arectangular wave voltage having a peak value 60 V is applied between thetransparent electrode layer 260 and the transparent electrode plate 262.The liquid crystal molecules in the UV curable liquid crystal layer 261are tilted by the voltage application. A tilt angle depends upon theapplied voltage.

[0279] The ultraviolet rays are irradiated onto the UV curable liquidcrystal layer 261 via a photo mask 263 under the condition that thevoltage is applied. The light shielding pattern is formed in the areasof the surface of the photo mask 263, except the areas corresponding tothe inclined surfaces of the projections 218. The intensity of theirradiated ultraviolet rays is 0.8 mW/cm², for example.

[0280] The polymerization reaction occurs in the portions of the UVcurable liquid crystal layer 261, that correspond to the inclinedsurfaces of the projections 218, according to the irradiation of theultraviolet rays. Then, the UV curable liquid crystal material that hasnot been polymerized is removed by cleaning the substrate. In thismanner, the compensating members 222 shown in FIG. 35 are formed.

[0281] The compensating members 222 formed in the above conditions havethe refractive anisotropy that has the direction parallel to theprojections 218 as the lag phase axis. The retardation is about 10 nm.The refractive anisotropy Δn of the compensating members 222 can bechanged by changing the voltage applied between the transparentelectrode layer 260 and the transparent electrode plate 262.

[0282] Eighth Embodiment

[0283] Next, a liquid crystal display device according to an eighthembodiment will be explained with reference to FIG. 37 and FIG. 38hereunder. In the liquid crystal display device according to the eighthembodiment, the compensating members 221, 222 shown in FIG. 35 in theseventh embodiment are not provided. The double refraction effect of theliquid crystal layer can be compensated by the refractive anisotropy ofthe projection itself. Other configuration is similar to theconfiguration of the liquid crystal display device according to theseventh embodiment.

[0284]FIG. 37 is a sectional view showing a projection 218 and itsneighborhood of an MVA liquid crystal display device according to theeighth embodiment. In this case, a projection on the TFT substrate 235side has the structure similar to that of the projection 218 shown inFIG. 37.

[0285] The projection 218 is separated into edge portions 218 apositioned in the peripheral areas, and an inner portion 218 bpositioned between the edge portions 218 a on both sides. The edgeportions 218 a has the refractive anisotropy, but the inner portion 218b has hardly the refractive anisotropy. The double refraction effect dueto tilted liquid crystal molecules 229 a in the neighborhood of the edgeportions 218 a can be compensated by the double refraction effect due tothe refractive anisotropy of the edge portions 218 a.

[0286] Then, a method of manufacturing the projections of the liquidcrystal display device according to the eighth embodiment will beexplained with reference to FIG. 38 hereunder. The surface of the commonelectrode 254 is rubbed in the direction parallel to the projections. AUV curable liquid crystal layer 265 of 1.5 μm is formed on the surfaceof the common electrode 254. The UV curable liquid crystal layer 265 isformed of the same material as the UV curable liquid crystal layer 261shown in FIG. 36 in the seventh embodiment.

[0287] An electric plate 266 is arranged to substantially come intocontact with the surface of the UV curable liquid crystal layer 265. Atransparent electrode pattern 267 that corresponds to an area serving asthe inner portions 218 b of the projections and another transparentelectrode pattern 268 arranged on both sides of the transparentelectrode pattern 267 are provided on the electric plate 266.

[0288] A rectangular wave voltage e1 is applied between the commonelectrode 254 and the transparent electrode pattern 267, and arectangular wave voltage e2 is applied between the common electrode 254and the transparent electrode pattern 268. The voltage e1 is higher thanthe voltage e2. The large electric field is generated in the areaserving as the inner portions 218 b of the UV curable liquid crystallayer 265 in the thickness direction. Therefore, the liquid crystalmolecules in this portion are aligned substantially perpendicularly tothe substrate surface. Since only the relatively small electric field isgenerated in the area serving as the inner portions 218 b, the liquidcrystal molecules in this portion are tilted to the substrate surface.

[0289] Under this condition, the ultraviolet rays are irradiated ontothe area of the UV curable liquid crystal layer 265, in which theprojections are to be formed, via the photo mask 269. The polymerizationreaction is caused in the area of the UV curable liquid crystal layer265, in which the projections are to be formed, by the irradiation ofthe ultraviolet rays. After the irradiation of the ultraviolet rays, theUV curable liquid crystal material in which the polymerization is notcaused is removed by cleaning the substrate. In this manner, theprojections shown in FIG. 37 are formed.

[0290] Projections 217 on the TFT substrate 235 are manufactured by thesimilar method. In this case, the pixel electrodes that are separatedevery pixel are formed on the TFT substrate 235. Therefore, after allTFTs are brought into their conductive state, the rectangular wavevoltage is applied between the drain bus line and the electrode plate266. since the TFTs are set to their conductive state, the rectangularwave voltage is applied to all pixel electrodes, and the electric fieldis generated in the UV curable liquid crystal layer.

[0291] As described above, according to the present invention, thedouble refraction effect of the liquid crystal layer due to the tilt ofthe liquid crystal molecules in the neighborhood of the edges of theprojections in the MVA liquid crystal display device can be reduced, andthe leakage light in the dark state can be prevented.

[0292] Ninth Embodiment

[0293] Next, a liquid crystal display device according to a ninthembodiment will be explained with reference to FIGS. 39A and 39Bhereunder. In the seventh embodiment, as shown in FIG. 35, both theprojections 217, 218 are formed of dielectric material. In the ninthembodiment, a surface of one projection is formed of conductive materialand other configurations are similar to the case in the seventhembodiment. In this case, the compensating members 221, 222 shown inFIG. 35 may be arranged as occasion demands.

[0294]FIG. 39A is a schematic partial sectional view showing a liquidcrystal display device according to the ninth embodiment. Projections217 are formed on the pixel electrode 212 on the TFT substrate 235. Avertical alignment film 228 on the TFT substrate 235 side is formed tocover the projections 217 and the pixel electrode 212. Projections 218 aformed of dielectric material are formed on a surface of a color filter251 on the opposing substrate 236 side.

[0295] A common electrode 254A is formed to cover the pixel electrode212 and the projections 218 a. The dielectric projection 218 a and aportion 218 b of the common electrode 254A for covering the dielectricprojections 218 a constitute a CF substrate side projection 218. Analignment film 228 on the opposing substrate 236 side is formed to coverthe common electrode 254A.

[0296]FIG. 39B is a plan view showing the liquid crystal layer to showthe tilt directions of the liquid crystal molecules when the voltage isapplied. When a predetermined voltage is applied between the pixelelectrode 212 and the common electrode 254A, the liquid crystalmolecules in the liquid crystal layer 229 are tilt d. The liquid crystalmolecules 229 a in the neighborhood of the inclined surfaces of theprojections 217 are tilted such that end portions that are remote fromthe pixel electrode 212 are positioned far from the center of theprojection 217.

[0297] The surfaces of the projections 218 are formed of the conductivematerial, the electric field concentrates into the surfaces of theprojections 218 and thus equipotential surfaces are generated along thesurfaces of the projections 218. Therefore, the liquid crystal moleculesin the neighborhood of the surfaces of the projections 218 are falleninto the direction parallel to the surfaces of the projections 218. Theliquid crystal molecules 229 b in the neighborhood of the top surfacesof the projections 218 are affected equally by the liquid crystalmolecules on both sides of the projections 218. Therefore, the liquidcrystal molecules 229 b are tilted along the extending direction of theprojections 218.

[0298] The liquid crystal molecules in the area between the projections217 and the projections 218 are tilted in the middle direction betweenthe tilt directions of the liquid crystal molecules 229 a and the liquidcrystal molecules 229 b. That is, the liquid crystal molecules arealigned like a bend orientation in the direction of the substratesurface.

[0299] Like the liquid crystal display device shown in FIG. 8 in theprior art, the polarizing plates are cross-nicol-arranged on the outsideof the TFT substrate 235 and the opposing substrate 236. Thepolarization axes 230 of the polarizing plates intersect with theextending direction of the projections 217 and the projections 218 inFIG. 39B by 45 degrees. When the light transmits through the area, inwhich the liquid crystal molecules are tilted in the direction inparallel with the polarization axes 230 of the polarizing plates, alongthe thickness direction of the liquid crystal layer, such light does notrotate the polarization axis. Therefore, the area in which the liquidcrystal molecules are tilted to intersect with the polarization axis by45 degrees becomes dark, and thus the black line appears between theprojection 217 and the projection 218.

[0300] The response time of the liquid crystal display device in theninth embodiment measured when the display is changed from the darkstate to the ¼ half tone state and then returned again to the dark stateis shorter than the response time of the MVA liquid crystal displaydevice shown in FIG. 8 in the prior art. The reason for this may beconsidered such that, since the liquid crystal molecules arebend-oriented in the substrate surface when the voltage is applied, thetilt direction can be defined more quickly.

[0301] In the ninth embodiment, the tilt direction of the liquid crystalmolecules 229 b shown in FIG. 39B become parallel with the lengthdirection of the dielectric projections 218, but the vertical direction,i.e., the upward or downward direction in FIG. 39B is not decided.Therefore, there is the case where two domains in which the tiltdirection is different by 180 degrees are generated. If the locations ofdomain boundaries are not fixed, display quality is degraded. In orderto prevent the degradation of the display quality due to variation ofthe locations of the domain boundaries, another dielectric projectionsintersecting with the projections 217, 218 may be provided on theopposing surface of another substrate. Since the liquid crystalmolecules on both sides of the intersecting dielectric projections tendsto tilt toward two directions different by 180 degrees mutually, thedomain boundaries are fixed at positions of the projections thatintersect with the projections 217, 218.

[0302] In the above ninth embodiment, one projections are formed as theconductive projections. In place of the conductive projections, adielectric film that has smaller dielectric constant than that of theliquid crystal layer may be formed on the opposing surface and thenrecess patterns may be formed on a surface of the dielectric film. Inthis case, when the voltage is applied between the substrates, theelectric field having a distribution similar to the case where thedielectric projections are formed is generated. Therefore, the liquidcrystal molecule alignment similar to the case where the dielectricprojections are provided can be obtained.

[0303] Also, in the ninth embodiment, in order to define the boundariesof the domains, the projections made of dielectric material are formedon the opposing surface of the substrate. But the slits may be formed inthe pixel electrode in lieu of the formation of the projections. Thedistribution of the electric field in the neighborhood of the slits whenthe slits are formed in the pixel electrode is similar to thedistribution of the electric field generated in the case where thedielectric projections are provided. Therefore, even if the slits areformed in the pixel electrode, the alignment of the liquid crystalmolecules similar to the case where the dielectric projections areformed can be achieved.

[0304] As described above, according to the present invention, when thevoltage is applied, the response characteristic can be improved byproviding the projections or the slits such that the liquid crystalmolecules are bend-oriented in the direction of the substrate surface.

[0305] Tenth Embodiment

[0306] Next, a liquid crystal display device according to a tenthembodiment will be explained with reference to FIG. 40 hereunder. FIG.40 is a schematic partial sectional view showing the liquid crystaldisplay device according to the tenth embodiment. The configuration ofthe TFT substrate 235 is similar to that of the TFT substrate 235 shownin FIGS. 39A and 39B in the ninth embodiment.

[0307] The common electrode 254 is formed on the surface of the colorfilter 251 on the opposing substrate 236. The vertical alignment film228B is formed to cover the surface of the common electrode 254B. Thealignment defining force is destroyed or weakened in the area 228 a ofthe vertical alignment film 228B, that correspond to the conductiveprojections 218 in FIG. 39A. The area in which the alignment definingforce is destroyed or weakened is called a nonalignment defining area.The nonalignment defining area can be formed by irradiating selectivelythe energy beam such as ultraviolet laser, infrared laser, etc. onto thevertical alignment film, for example.

[0308] When the voltage is not applied, the liquid crystal molecules inthe area of the alignment film 228 b other than the nonalignmentdefining area 228 a are aligned substantially perpendicularly to thesubstrate surface. Since the liquid crystal molecules that come intocontact with the nonalignment defining area 228 a have the weak verticalalignment force, they are tilted to the substrate surface. It seemsthat, since the liquid crystal molecules in the almost middle of thenonalignment defining area 228 a are affected by the liquid crystalmolecules on both sides, the tilt direction of the liquid crystalmolecules become parallel with the length direction of the nonalignmentdefining area 228 a.

[0309] When the voltage is applied between the substrates, the liquidcrystal molecules in the nonalignment defining area 228 a are largelytilted toward the length direction of the nonalignment defining area 228a. As a result, the nonalignment defining area 228 a can achieve thesimilar effect to the conductive projections 218 shown in FIG. 39A.

[0310] Eleventh Embodiment

[0311] Next, a liquid crystal display device according to an eleventhembodiment will be explained with reference to FIGS. 41A and 41Bhereunder.

[0312]FIG. 41A is a partial sectional view showing the liquid crystaldisplay device according to the eleventh embodiment. In the ninthembodiment, as shown in FIGS. 39A and 39B, the TFT substrate sideprojections 217 and the CF substrate side conductive projections 218 arearranged alternately in the substrate surface. In the eleventhembodiment, if viewed along the normal direction of the substrate, theTFT substrate side projections 217 and the CF substrate side conductiveprojections 218 are overlapped mutually.

[0313]FIG. 41B is a plan view showing the liquid crystal layer to showthe tilt directions of liquid crystal molecules when the voltage isapplied. If the predetermined voltage is applied between the pixelelectrode 212 and the common electrode 254A, the liquid crystalmolecules in the liquid crystal layer 229 are tilted. The liquid crystalmolecules 229 c in the neighborhood of the inclined surfaces of theprojections 217 are tilted such that end portions that are remote fromthe pixel electrode 212 are positioned far from the center of theprojection 217. The liquid crystal molecules 229 d in the neighborhoodof the top portions of the projections 218 are tilted toward theextending direction of the projections 218. The liquid crystal moleculesin the area between the middle portions and the edge portions of theprojections 217, 218 are tilted in the intermediate direction betweenthe tilt direction of the liquid crystal molecules 229 c and the tiltdirection of the liquid crystal molecules 229 d. That is, the liquidcrystal molecules are splay-oriented in the neighborhood of theprojections 217, 218.

[0314] In this manner, since the conductive projections 218 are arrangedto overlap with the conductive 217, the tilt direction of the liquidcrystal molecules in the almost middle area on the top portion of theprojections are restricted in the extending direction of the projections217, 218. Therefore, when the voltage is applied, the alignment changeof the liquid crystal molecules can be accelerated much more rather thanthe case where the conductive projections 218 are not provided.

[0315] In addition, since the TFT substrate side projections 217 and theCF substrate side conductive projections 218 are overlapped mutually,the relatively large electric field is generated between twoprojections. For this reason, it may be considered that the alignmentchange of the liquid crystal molecules is carried out quickly and thusthe response characteristic can be improved.

[0316] Twelfth Embodiment

[0317] Next, a liquid crystal display device according to a twelfthembodiment will be explained with reference to FIG. 42 and FIG. 43hereunder.

[0318]FIG. 42 is a sectional view showing the liquid crystal displaydevice according to the twelfth embodiment. The nonalignment definingarea 228 a is formed in a part of the alignment film 228 c on the TFTsubstrate side, and the dielectric projections 218 are formed on thesurface of the common electrode 254 on the opposing substrate 236. Ifviewed along the normal direction of the substrate, the nonalignmentdefining area 228 a and the dielectric projections 218 are overlappedmutually.

[0319]FIG. 43 is a plan view showing the liquid crystal display deviceaccording to the twelfth embodiment. The configurations of the gate busline 205, the drain bus line 207, the TFT 210, and the pixel electrode212 are similar to those in the liquid crystal display device shown inFIG. 33 according to the seventh embodiment. In FIG. 43, the descriptionof the capacitive bus line 208 shown in FIG. 33 is omitted. A sectionalview taken along a X-X dot-dash line in FIG. 43 corresponds to FIG. 42.The CF substrate side dielectric projections 218 and the nonalignmentdefining area 228 a extend longitudinally in the almost middle area ofthe pixel electrode 212 in the direction parallel to the drain bus line207.

[0320] If the voltage is applied between the pixel electrode 212 and thecommon electrode 254, liquid crystal molecules 229 e in the neighborhoodof the inclined surfaces of the dielectric projections 218 are tiltedsuch that end portions that are remote from the opposing substrate 236are positioned far from the center of the dielectric projection 218. Theliquid crystal molecules 229 f in the neighborhood of the center portionof the nonalignment defining area 228 a are tilted in the lengthdirection (longitudinal direction in FIG. 43) of the nonalignmentdefining area 228 a. Hence, like the case of the eleventh embodimentshown in FIG. 41, the liquid crystal molecules are splay-oriented.Therefore, when the voltage is applied, the alignment change of theliquid crystal molecules can be accelerated much more rather than thecase where the nonalignment defining area 228 a is not provided.

[0321] The liquid crystal molecules 229 g in the neighborhood of theedge portions of the pixel electrode 212 are tilted toward the inside ofthe pixel electrode 212 by the disturbance of the electric field so asto orthogonally intersect with the edges. The liquid crystal moleculesbetween the longitudinal edges of the pixel electrode 212 and thedielectric projections 218 are tilted in the middle direction betweenthe tilt direction of the liquid crystal molecules 229 f and the tiltdirection of the liquid crystal molecules 229 g.

[0322] In FIG. 43, the liquid crystal molecules in the neighborhood ofthe upper and lower edge portions of the pixel electrode 212 are tiltedtoward the inside of the pixel electrode 212. Therefore, the tiltdirection of the liquid crystal molecules 229 f in the middle portion ofthe projections 218 is defined in the longitudinal direction in FIG. 43,but their directions are opposite mutually. As a result, domainboundaries are generated in the inside of the pixel. Since thedielectric projections are arranged between the alignment film 228C ofthe TFT substrate 235 in FIG. 42 and the pixel electrode 212 so as toorthogonally intersect with the nonalignment defining area 228 a, thedomain boundaries can be fixed at the positions of the dielectricprojections.

[0323] Thirteenth Embodiment

[0324] Next, a liquid crystal display device according to a thirteenthembodiment will be explained with reference to FIG. 44 hereunder.

[0325]FIG. 44 is a plan view showing the liquid crystal display deviceaccording to the thirteenth embodiment. The configurations of the gatebus line 205, the drain bus line 207, the TFT 210, and the pixelelectrode 212 are similar to those in the liquid crystal display deviceshown in FIG. 33 according to the seventh embodiment. In FIG. 44, thedescription of the capacitive bus line 208 shown in FIG. 33 is omitted.The nonalignment defining area 228 b is formed in a part of thealignment film on the TFT substrate and the opposing substrate. In thiscase, the projections for defining the domain boundaries are not formedon both substrates.

[0326] The shape of the pixel electrode 212 has notches to match withthe shape of the TFT 210, but is basically approximated by a rectangle.The nonalignment defining areas 228 b extend from respective corners ofthe rectangle toward the inside of the pixel. The nonalignment definingareas 228 b extending from r spective corners are coupled mutually inthe inside of the pixel.

[0327] The tilt directions of the liquid crystal molecules in theneighborhood of two sides intersecting with one corner of the pixelelectrode 212 are not parallel mutually. Therefore, the domainboundaries are generated between two sides. In the thirteenthembodiment, since the nonalignment defining areas 228 b extend from thecorners toward the inside of the pixel, such nonalignment defining areas228 b act as the domain boundaries. That is, one domain can be definedby one side of the pixel electrode 212 and the nonalignment definingareas 228 b.

[0328] In the thirteenth embodiment, the locations of the domainboundaries are restricted by the nonalignment defining areas 228 bwithout the projections. Accordingly, reduction in the opticaltransmittance due to the projections can be prevented.

[0329] Fourteenth Embodiment

[0330] Next, a liquid crystal display device according to a fourteenthembodiment will be explained with reference to FIGS. 45A and 45Bhereunder.

[0331]FIGS. 45A and 45B are plan views showing a local portion in onepixel of the liquid crystal display device according to the fourteenthembodiment. Two nonalignment defining areas 228 c in which the alignmentdefining force of the vertical alignment film is destroyed or weakenedare arranged in parallel with each other. When the voltage is notapplied, as shown in FIG. 45A, the liquid crystal molecules 229 ipositioned between two nonalignment defining areas 228 c are alignedsubstantially perpendicularly to the substrate surface.

[0332] The liquid crystal molecules 229 h on the inside of thenonalignment defining area 228 c are tilted slightly from theperpendicular direction since the vertical alignment defining force inthis area is weak. The tilt direction coincides with the lengthdirection of the nonalignment defining area 228 c. This may beconsidered such that, since the tilt direction is affected equally bythe liquid crystal molecules on both sides of the nonalignment definingareas 228 c, such tilt direction is not shifted to one of both sides.Accordingly, it seems that, if the influence by the liquid crystalmolecules on both sides is weakened, the tilt direction of the liquidcrystal molecules on the inside of the nonalignment defining areas 228 cbecome random. In order to restrict the tilt direction of the liquidcrystal molecules by the nonalignment defining areas 228 c, the widthmust be reduced narrower than a certain upper limit value. According tothe experiment made by the inventors of this application, when the widthof the nonalignment defining area 228 c is 5 μm, the liquid crystalmolecules on the inside are tilted to the length direction of thenonalignment defining areas 228 c.

[0333]FIG. 45B shows the alignment states of the liquid crystalmolecules when the voltage is applied. The liquid crystal molecules onthe inside of the nonalignment defining areas 228 c are largely tiltedto the inclined direction when the voltage is not applied. The liquidcrystal molecules 229 i between two nonalignment defining areas 228 care affected by the inclination of the liquid crystal molecules 229 hand are tilted to the direction parallel to the length direction of thenonalignment defining areas 228 c.

[0334] In this way, it is possible to restrict the tilt direction of theliquid (crystal molecules by providing not the nonalignment definingareas 228 c but the projections. Since the projections are not provided,reduction in the optical transmittance due to the projections can beprevented.

[0335] With the use of JALS-684 manufactured by JSR Inc. as thealignment film and MJ961213R manufactured by Merck Inc. as the liquidcrystal material, the liquid crystal cell in which a width of thenonalignment defining area 228 c is 5 μm, an interval is 35 μm, and acell thickness is 4.25 μm is fabricated. The polarizing plates arecross-nicol-arranged such that their polarizations axis directionsintersect with the length direction of the nonalignment defining area228 c by an angle of 45 degrees. After the transmittance of the liquidcrystal display device is measured, the maximum transmittance in excessof 25% has been confirmed. Here, the intensity of the ultraviolet raysirradiated to form the nonalignment defining area 228 c is 4000 mJ/cm².

[0336] Fifteenth Embodiment

[0337] Next, a liquid crystal display device according to a fifteenthembodiment will be explained with reference to FIG. 46 hereunder.

[0338]FIG. 46 is a plan view showing the alignment state of the liquidcrystal molecules in the light state of the liquid crystal displaydevice according to the fifteenth embodiment. The liquid crystal displaydevice according to the fifteenth embodiment is different from theliquid crystal display device according to the fourteenth embodiment inthat a chiral agent is added into the liquid crystal layer. Otherconfigurations are similar to those in the liquid crystal display deviceaccording to the fourteenth embodiment. CM31 manufactured by Chisso Inc.is employed as the chiral agent, and a concentration of the chiral agentused in the liquid crystal material is set to 4.8 wt %.

[0339] It has been found that, when the light state of the liquidcrystal display device according to the fifteenth embodiment ismonitored, the light transmits through the center portion of thenonalignment defining area 228 c and thus four dark lines appear betweentwo neighboring nonalignment defining areas 228 c. Since the areas inwhich the tilt directions of the liquid crystal molecules are parallelwith the polarization axes of the polarizing plates do not exhibit thedouble refraction property, such areas are the dark areas even when thevoltage is applied. The reason for the appearance of four dark lines isthat the director directions of the liquid crystal molecules are twistedin compliance with the displacement from one nonalignment defining area228 c to the neighboring nonalignment defining area 228 c. Also, itseems that the liquid crystal molecules are tilted to the lengthdirection of the nonalignment defining area 228 c in the center portionof the nonalignment defining area 228 c. A twisted angle may be 360degrees between the neighboring nonalignment defining areas 228 cbecause the number of the dark lines is four.

[0340] In the fifteenth embodiment, since the dark line appears in thelight state, no improvement can be found in a respect of thetransmittance rather than the prior art. However, it is expected that,since the tilt direction of the liquid crystal molecules is decided bythe chiral agent, the response speed from the dark state to the halftone state can be accelerated.

[0341] Sixteenth Embodiment

[0342]FIG. 47 is a plan view showing an MVA liquid crystal displaydevice according to a sixteenth embodiment of the present invention.FIG. 48 is a sectional view showing the liquid crystal display device.In this case, FIG. 48 shows a sectional shape at a position taken alonga XI-XI line in FIG. 47. FIG. 47 shows one pixel of the liquid crystaldisplay device, and a chain double-dashed line in FIG. 47 denotes aposition of the projection (a domain defining projection and anauxiliary projection) formed on the opposing substrate side.

[0343] A plurality of gate bus lines 312 are formed in parallel witheach other on a glass substrate (TFT substrate) 311. Also, capacitivebus lines 313 are formed in parallel with gate bus lines 312 between thegate bus lines 312 respectively. In addition, a gate electrode 316 g ofthe TFT 316 is formed on the glass substrate 311. The gate electrode 316g is connected to the gate bus line 312. The gate bus line 312, the gateelectrode 316 g,and the capacitive bus line 313 are formed on the samewiring layer (first wiring layer). That is, the gate bus line 312, thegate electrode 316 g, and the capacitive bus line 313 are formed bypatterning the same conductive film. Also, the gate bus line 312, thegate electrode 316 g, and the capacitive bus line 313 are covered with afirst insulating film (gate insulating film) 314 formed on the glasssubstrate 311.

[0344] A silicon film (not shown) serving as the active area of the TFT316 is formed on the first insulating film 314 over the gate electrode316 g. Also, a plurality of drain bus lines 315, and a source region 316s and a drain region 316 d of the TFT 316 are formed on the insulatingfilm 314. The drain bus lines 315 are formed to orthogonally intersectwith the gate bus lines 312. The source region 316 s and the drainregion 316 d are formed on both sides of the silicon film over the gateelectrode 316 g to be separated mutually. Then, the drain region 316 dis connected to the drain bus line 315.

[0345] Rectangular areas partitioned by the gate bus lines 312 and thedrain bus lines 315 are pixel areas respectively. The drain bus lines315, and the source region 316 s and the drain region 316 d are formedon the same wiring layer (second wiring layer). The drain bus lines 315and the TFT 316 are covered with the second insulating film 317 formedon the first insulating film 314.

[0346] The pixel electrodes 318 are formed on the second insulating film317 every pixel area. For example, the pixel electrodes 318 are formedof transparent conductor such as ITO, etc. Slits 319 aligned on astraight line extending in the oblique direction are formed in the pixelelectrode 318. In the sixteenth embodiment, the slits 319 are arrangedin a vertically symmetric fashion in one pixel electrode 318. Also, thepixel electrode 318 is connected electrically to the source electrode316 s via a contact hole formed in the second insulating film 317.

[0347] A vertical alignment film 320 is formed on the pixel electrode318. The vertical alignment film 320 is formed polyimide, for example.As described later, a process for revealing partially (a shaded portion321 in FIG. 47) a pre-tilt angle (pre-tilt angle revealing process) isapplied to the alignment film 320. As the pre-tilt angle revealingprocess, for example, there are UV irradiation, rubbing process, or thelike. By applying the pre-tilt angle revealing process, under thecondition that the voltage is not applied, the liquid crystal moleculesare tilted to the predetermined direction and an angle between thealignment film 320 and the director of the liquid crystal molecules(pre-tilt angle) is more than 45 degrees and less than 90 degrees. Inthe sixteenth embodiment, the preferable range of the pre-tilt angle is87 to 89 degrees.

[0348] In contrast, a black matrix 332 is formed under the glasssubstrate (opposing substrate) 331. The areas of the gate bus lines 312,the capacitive bus lines 313, the drain bus lines 315, and the TFTs 316on the TFT substrate side and the outside area of the display area arelight-shielded by the black matrix 332. In the sixteenth embodiment, itis assumed that the black matrix 332 is formed of a light-shieldingmetal film such as Cr (chromium), etc. However, the black matrix 332 maybe formed of black resin. In addition, the black matrix 332 may beformed by laminating at least two-colored color filters out of red (R),green (G), and blue (B) color filters, to be described later.

[0349] Any one one-colored color filter 333 of red (R), green (G), andblue (B) color filters is formed under the glass substrate 331 everypixel. In the sixteenth embodiment, it is assumed that the red (R),green (G), and blue (B) color filters are arranged repeatedly insequence in the horizontal direction and also the same-colored colorfilters are arranged in the vertical direction.

[0350] The common electrode 334 common to respective pixel electrodes isformed under the color filter 333. The common electrode 334 is alsoformed of transparent conductor such as ITO, etc. The domain definingprojections (also called banks) 336 are formed under the commonelectrode 334. As shown in FIG. 47, the projections 336 are arranged atthe middle position between the slits 319 provided in the pixelelectrode 318 on the TFT substrate side. Also, auxiliary projections(called auxiliary banks) 336 a are formed at positions that coincidewith both edge portions of the pixel electrode 318 in the horizontaldirection, more particularly, portions at which the projections 336 forman obtuse angle with the edge of the pixel electrode 318. The auxiliaryprojections 336 a are formed simultaneously of the same material as thedomain defining projections 336.

[0351] The vertical alignment film 335 is formed under the glasssubstrate 331. Surfaces of the common electrode 334, the projections336, and the auxiliary projections 336 a are covered with the alignmentfilm 335. The alignment film 335 is formed of polyimide, for example.

[0352] Liquid crystal material 329 having the negative dielectricanisotropy is sealed between the TFT substrate (glass substrate 311) andthe opposing substrate (glass substrate 331). Spherical spacers having auniform diameter, for example, are arranged between the TFT substrate(glass substrate 311) and the opposing substrate (glass substrate 331),so that a distance (cell gap) between the TFT substrate and the opposingsubstrate is kept constant. Also, the polarizing plate (not shown) isarranged below the TFT substrate (glass substrate 311) and over theopposing substrate (glass substrate 331) respectively.

[0353] In the sixteenth embodiment, the pre-tilt angle revealing processis applied to the portion of the alignment film 320 on the TFT substrateside, which are the edge portions of the pixel electrode 318 on both sids in the horizontal direction and at which the projections. 336 have anobtuse angle with the edge of the pixel electrode 318 (in other words,portions at which the slit series have an acute angle with the auxiliaryprojections 336 a), and the adjacent pixel side half area on the insideof the slit 319 a whose end portion on the pixel side next to the rightside in FIG. 47 (referred to as the “adjacent pixel” hereinafter) isclosed and which is closest to the adjacent pixel (shaded area indicatedby a reference 321 in FIG. 47). The effect obtained by applying thepre-tilt angle revealing process to these areas will be explained withreference to schematic views of the pixel electrode shown in FIG. 49 toFIG. 51. In this case, in FIG. 49 to FIG. 51, it is indicated that theblack dot portions of the liquid crystal molecules 328 are directed tothe common electrode side.

[0354] If there is no positional displacement when the TFT substrate andthe opposing substrate are stuck together, the auxiliary projections 336a on the adjacent pixel side are arranged to coincide with the edge ofthe pixel electrode 318, as shown in FIG. 49. The liquid crystalmolecules 328 are aligned in the direction perpendicular to the inclinedsurface of the auxiliary projections 336 a in the neighborhood of theauxiliary projections 336 a. Also, the liquid crystal molecules in thehalf area of the slit 319 a whose end on the adjacent pixel side isclosed and which is closest to the adjacent pixel on the adjacent pixelside are affected by the liquid crystal molecules 328 in theneighborhood of the auxiliary projections 336 a and then aligned in thepredetermined directions (directions shown in FIG. 49 respectively).

[0355] In the case that the auxiliary projections 336 a are not providedor positions of the auxiliary projections 336 a are displaced toward theadjacent pixel side as shown in FIG. 50, when the voltage is appliedbetween the pixel electrode 318 and the common electrode 334, the liquidcrystal molecules in the neighborhood of the edge of the pixel electrode318 are tilted to the direction (direction indicated by an arrow B inFIG. 50) to which the liquid crystal molecules 328 on the inside of theslit 319 b closest to the drain bus line 315 of the adjacent pixel aretilted. However, since this direction is different from the direction towhich the liquid crystal molecules are tilted by the electric fieldgenerated by the drain bus line 315 of the adjacent pixel, the alignmentbecomes unstable and thus the response characteristic is degraded or thealignment failure is generated.

[0356] As shown in FIG. 51, if the pre-tilt angle revealing process isapplied the alignment film 320 in the portion 321 in which the alignmentof the liquid crystal molecules becomes unstable due to the lateralelectric field generated by the drain bus line 315 of the adjacentpixel, i.e., the inner portion of the slit 319 a on the adjacent pixelside and the portion in which the projections 336 form an obtuse anglewith the edge of the pixel electrode 318, the liquid crystal moleculesare hardly affected by the lateral electric field generated by the drainbus line 315 of the adjacent pixel since the liquid crystal moleculesare tilted to the predetermined direction (direction indicated by anarrow C in FIG. 51) in the initial state. As a result, the alignmentfailure can be avoided and the response characteristic can be improved.

[0357] Next, a method of manufacturing the liquid crystal display deviceaccording to the sixteenth embodiment will be explained with referenceto FIG. 47 and FIG. 48 hereunder.

[0358] First, the gate bus line 312, the gate electrode 316 g and thecapacitive bus line 313 are formed by forming a Cr film of about 150 nmthickness, for example, as a conductive film on the glass substrate (TFTsubstrate) 311 by the PVD (Physical Vapor Deposition) method and thenpatterning the conductive film by the photolithography.

[0359] Then, an insulating film 314 serving as the gate insulating filmof the TFT 316, an n⁻-type amorphous silicon film serving as the activeregion of the TFT 316, and an insulating film serving as the channelprotection film are formed in sequence on the overall upper surface ofthe glass substrate 311 by the plasma CVD method.

[0360] The insulating film 314 is formed of silicon nitride (SiN) orsilicon oxide (SiO₂), for example, to have a thickness of about 100 to600 nm. Also, a thickness of the n⁻-type amorphous silicon film is about15 to 50 nm. In addition, the insulating film serving as the channelprotection film is formed of silicon nitride, for example, to have athickness of about 50 to 200 nm.

[0361] Then, the channel protection film is formed by patterning theuppermost layer of the insulating film by the photolithography. Then,the conductive film having a triple-layered structure of Ti, Al and Tiis formed by forming an n⁺-type amorphous silicon film serving as anohmic contact layer of the TFT 316 to have a thickness of about 30 nm,and then stacking Ti, Al, and Ti in sequence on the n⁺-type amorphoussilicon film by the PVD method. For example, a thickness of theunderlying Ti layer is 20 nm, a thickness of the Al layer is 75 nm, anda thickness of the overlying Ti layer is 20 nm. This conductive film maybe formed of Al, Al alloy, or other low resistance metal.

[0362] Then, a resist film having a predetermined pattern is formed onthe conductive film by using the photoresist. Then, as shown in FIG. 48,the source electrode 316 s and the drain electrode 316 d of the TFT 316as well as the drain bus lines 315 are formed by etch the conductivefilm, the n⁺-type amorphous silicon film, and the n⁻-type amorphoussilicon film using the resist film as an etching mask. The conductivefilm, the n⁺-type amorphous silicon film, and the n⁻-type amorphoussilicon film are etched by the dry etching using a mixed gas of Cl₂ andBCl₃, for example. After this, the resist film used as the etching maskis removed.

[0363] Then, for example, a silicon nitride film as the insulating film(protection film) 317 is formed on the overall upper surface of theglass substrate 311 by the CVD method to have a thickness of about 100to 600 nm. Then, a contact hole is formed in the insulating film 317 toreach the source electrode 316 s of the TFT 316.

[0364] Then, the ITO film of about 70 nm thickness is formed on theoverall upper surface of the glass substrate 311 by the PVD method.Then, as shown in FIG. 47, the pixel electrode 318 having the slits 319is formed by patterning the ITO film by the photolithography.

[0365] In turn, the alignment film 320 is formed on the overall uppersurface of the glass substrate 311. Then, the pre-tilt angle revealingprocess is applied to predetermined portions (portions indicated by areference 321 in FIG. 47) of the alignment film 320. As the pre-tiltangle revealing process, there are the UV irradiation and the rubbingprocess, for example. If the pre-tilt angle is revealed by the UVirradiation, material in which the pre-tilt angle is revealed by the UVirradiation, e.g., polyimide or polyamic acid that is alignment filmmaterial for the UV alignment is used as alignment film material, thencovering the portions of the alignment film 320 other than thepredetermined portions 321 with the light-shielding mask, and thenirradiating the polarized UV onto the substrate 311 from the obliquedirection, e.g., the direction indicated by an arrow C in FIG. 51.According to the material of the alignment film 320, the pre-tilt anglecan be revealed by irradiating the non-polarized UV.

[0366] In contrast, if the pre-tilt angle is revealed by the rubbingprocess, for example, an alignment film JALS684 manufactured by JSR Inc.is used as alignment film material, then areas of the alignment film 320other than the predetermined portions 321 is covered with the resistmask, etc., and then surfaces of the predetermined portions 321 of thealignment film 320 are rubbed by the nylon brush, etc. along thepredetermined direction, e.g., the direction indicated by an arrow C inFIG. 51. At this time, the pre-tilt angle can be changed by adjustingthe revolution number of the brush, the rubbing depth and the number ofrubbing. In this manner, the TFT substrate can be completed.

[0367] In contrast, the opposing substrate having the projections 336,336 a is prepared. The opposing substrate can be manufactured by thewell known method. More particularly, the black matrix 332 having apredetermined pattern is formed of light shielding material such as Cr,etc. on the glass substrate 331. Then, the red (R), green (G), and blue(B) color filters 333 are formed on the glass substrate 331 and then thecommon electrode 334 is formed of ITO on the color filters 333. Then,the domain defining projections 336 and the auxiliary projections 336 aare formed on the common electrode 334, and then the surfaces of thecommon electrode 334, the projections 336, and the auxiliary projections336 a are covered with the alignment film 334 formed of polyimide.Accordingly, the opposing substrate can be completed.

[0368] Subsequently, the opposing substrate on which the domain definingprojections are provided and the TFT substrate formed in the abovemanner are stuck together, and then the liquid crystal material issealed between both substrates. Accordingly, the liquid crystal displaydevice according to the sixteenth embodiment can be completed.

[0369] In the above manufacturing method, the projections 336 and theauxiliary projections 336 a are formed of photoresist. But they are notlimited to the above. For example, the projections 336 and the auxiliaryprojections 336 a may be formed of dielectric material except for thephotoresist.

[0370] As described above, according to the liquid crystal displaydevice of the present invention, the domain defining projections areprovided on one substrate and the slits are formed on the electrode ofthe other substrate, and also the pre-tilt angle revealing process isapplied to the alignment film on the other substrate in the area inwhich the alignment of the liquid crystal molecules becomes unstable bythe lateral electric field from the bus line. Therefore, the alignmentfailure due to the lateral electric field from the bus line can beavoided, and the large aperture ratio, the good viewing anglecharacteristic, and the good picture quality can be achieved.

[0371] Seventeenth Embodiment

[0372]FIG. 52 is a plan view showing a liquid crystal display deviceaccording to a seventeenth embodiment of the present invention. Adifference of the seventeenth embodiment from the sixteenth embodimentis that the slits formed in the pixel electrode have a different shape,and thus the explanation of portions overlapped with the sixteenthembodiment will be omitted. Also, in FIG. 52, the case is shown wherethe auxiliary projections 336 a are arranged at the positions deviatedto the drain bus line 315 side of the adjacent pixel.

[0373] In the seventeenth embodiment, as shown in FIG. 52, the shape ofthe slit 319 b which is formed in the pixel electrode 318 and is closestto the adjacent pixel (i.e., the slit whose end portion on the adjacentpixel side is opened) has a taper shape in which a width of the endportion on the adjacent pixel side (referred to as the rear end sidehereinafter) is wide and a width of the end portion opposite to theadjacent pixel (referred to as the top end side hereinafter) is narrow.Also, the slit 319 that is adjacent to the slit 319 b, i.e., the slit119 a whose rear end side is closed and which is closest to the adjacentpixel, has a shape having a large width on the rear end side. That is,in the seventeenth embodiment, a width of the top end side of the slit319 b is set wider than that of the rear end side of the slit 319 a.

[0374] When the voltage is applied between the pixel electrode 318 andthe common electrode 334, as shown in FIG. 52, the liquid crystalmolecules 328 on the inside of the slit 319 b are tilted toward thedirection indicated by an arrow D in FIG. 52. In contrast, the liquidcrystal molecules 328 on the rear end side of the slit 319 a are tiltedtoward the direction indicated by an arrow E in FIG. 52. At this time,since the width of the slit 319 a on the rear end side is larger thanthat of the slit 319 b on the top end side and also the number of theliquid crystal molecules 328 on the rear end side of the slit 319 a islarger than that of the liquid crystal molecules 328 on the top end sideof the slit 319 b, the liquid crystal molecules 328 on the rear end sideof the slit 319 a are aligned in the predetermined direction (directionindicated by an arrow E). Also, the liquid crystal molecules in theneighborhood of the slit 319 a are also affected by the liquid crystalmolecules 328 on the inside of the slit 319 a and then aligned in thepredetermined direction. Therefore, the alignment failure can beavoided.

[0375] In the seventeenth embodiment, as described above, it is featuredthat the slit 319 b and the slit 319 a that are close to the adjacentpixel are formed like a taper shape. If the pre-tilt angle revealingprocess is applied to the predetermined portion of the alignment film,like the sixteenth embodiment, in addition to that the slit 319 b andthe slit 319 a are formed like a taper shape, the alignment failure dueto the lateral electric field from the drain bus line 315 of theadjacent pixel can be prevented without fail.

[0376] Besides, in the sixteenth and seventeenth embodiments, the slitsare formed in the pixel electrode on the TFT substrate side and thedomain defining projections and the auxiliary projections are providedon the opposing substrate side. But the present invention is not limitedto the above. For example, the present invention may be applied to theliquid crystal display device in which the domain defining projectionsand the auxiliary projections are provided on the pixel electrode on theTFT substrate side and the slits are formed in the common pixelelectrode on the opposing substrate side.

[0377] According to the liquid crystal display device of the presentinvention, the domain defining projections are provided on one substrateand also the slits are formed in the electrode on the other substrate,and the width of the end portion of the first slit closest to the busline of the adjacent pixel on the opposite side to the bus line is setsmaller than the width of the end portion of the second slit adjacent tothe first slit on the bus line side. Therefore, the alignment failuredue to the lateral electric field from the bus line of the adjacentpixel can be avoided, and the large aperture ratio, the good viewingangle characteristic, and the good picture quality can be achieved.

[0378] Eighteenth Embodiment

[0379] An eighteenth embodiment of the present invention will beexplained hereunder.

[0380] In Patent Application Publication (KOKAI) Hei 11-84414, it hasbeen proposed that the distribution of the dielectric constant of theresin is arranged symmetrically by changing gradually. However, there isno disclosure about the optimum combination with the projections and theslits.

[0381]FIG. 53 is a plan view showing a liquid crystal display deviceaccording to an eighteenth embodiment of the present invention, and FIG.54 is a schematic sectional view showing the liquid crystal displaydevice according to the eighteenth embodiment. In this case, in FIG. 53and FIG. 54, the same references are affixed to the same constituentelements as the sixteenth embodiment. Also, in FIG. 54, illustration ofthe insulating film and the alignment film on the TFT substrate side andthe black matrix, the color filter, the alignment film, etc. on theopposing substrate side is omitted.

[0382] Like the sixteenth embodiment, the gate bus line 312, the drainbus line 315, the TFT 316, the pixel electrode 318 and the verticalalignment film are formed on the TFT substrate 311 side. Also, thedomain defining slits 319 are formed in the pixel electrode 318. Asshown in FIG. 53, these domain defining slits 319 are arranged such thatthey are aligned on a straight line extending in the oblique directionand are positioned symmetrically in one pixel electrode 318.

[0383] In contrast, the black matrix, the color filter, and the commonelectrode 334 are formed on the opposing substrate side, and thedielectric film 338 of about 2 to 3 μm thickness is formed under thecommon electrode 334. The dielectric film 338 consists of a lowdielectric constant portion 338 a and a high dielectric constant portion338 b. The low dielectric constant portion 338 a is arranged in parallelwith the slit 319 in the middle between the domain defining slits 319 onthe TFT substrate 311 side. Also, the high dielectric constant portion338 b is arranged in the remaining area (containing the portion opposingto the slit 319). Then, the relative dielectric constant of the lowdielectric constant portion 338 a is 3.0, for example, and the relativedielectric constant of the high dielectric constant portion 338 b is3.5, for example.

[0384] As a method of forming the dielectric film 338 having theportions whose relative dielectric constant is different mutually,following methods may be considered.

[0385] As a first method, there is a method of patterning the substanceshaving different relative dielectric constant by the lithography. Moreparticularly, the high dielectric constant portion 338 b is formed byforming the SiN film by the CVD method and then patterning the SiN filmby the photolithography. Then, the photoresist is coated as material ofthe low dielectric constant portion 338 a, and then the resist filmcoated on the high dielectric constant portion 338 b is removed via theexposing and developing steps. Accordingly, the dielectric film 338having the low dielectric constant portion 338 a and the high dielectricconstant portion 338 b is formed. In this case, the relative dielectricconstant of the SiN is about 7 and the relative dielectric constant ofthe resist is about 3.

[0386] As a second method, there is a method of changing partially therelative dielectric constant of the dielectric film by irradiating thelight onto the dielectric film. For example, the dielectric film 338 isformed by coating polyvinyl cinnamate or polyimide having thephotoreaction group, etc. on the common electrode 334. In the case ofpolyvinyl cinnamate, the bridge reaction is accelerated by irradiatingthe light and thus the relative dielectric constant of thelight-irradiated portion is enhanced. In contrast, in the case ofmaterial that is split by the light such as polyimide, a molecularweight of the light-irradiated portion is reduced and thus thedielectric constant is lowered. As the material whose dielectricconstant is changed by the light irradiation, there are acrylic resin(methacrylate), and others.

[0387]FIG. 55 is a view showing equipotential lines when the voltage isapplied between the pixel electrode and the common electrode. As shownin FIG. 55, the equipotential lines are pushed out to the outside fromthe liquid crystal layer in the portion of the slit 319 of the pixelelectrode 318 and the low dielectric constant portion 338 a in thedielectric film 338 (portion encircled by a broken line in FIG. 55).Because the liquid crystal molecules having the negative dielectricanisotropy tend to be aligned along the equipotential lines, as shown inFIG. 54, the alignment direction of the liquid crystal molecules isdifferent respectively on both sides of the slit 319 and the lowdielectric constant portion 338 a, whereby alignment division (multidomain) can be attained.

[0388] In the eighteenth embodiment, since the alignment division (multidomain) can be attained by the dielectric film 338 having the lowdielectric constant portion 338 a and the high dielectric constantportion 338 b in place of the domain defining projections, the apertureratio can be improved and the liquid crystal display device which isbright and has high resolution can be implemented. Also, the portionshaving the different dielectric constant can be relatively easily formedby the photolithography or the light irradiation.

[0389]FIG. 56 is a graph showing the result to check whether or notdisclination is generated after the dielectric film 338 is formed byusing two type dielectric materials. In FIG. 56, dielectric materialthat is arranged at the positions opposing to the slits is used as thefirst dielectric material, and dielectric material that is arranged inthe middle of the slits is used as the second dielectric material.

[0390] As shown in FIG. 56, the relative dielectric constant of thesecond dielectric material is lower than that of the first dielectricmaterial. If difference of relative dielectric constant between them isless than 0.5, no disclination is generated, but the area which has theunstable alignment state is generated.

[0391] In addition, if the relative dielectric constant of the seconddielectric material is lower than that of the first dielectric materialby more than 0.5, the disclination is not generated and the good displayquality can be derived. If the relative dielectric constant of thesecond dielectric material is equal to or higher than that of the firstdielectric material, the disclination is generated.

[0392] In case the high dielectric constant portion 338 b is arranged inthe middle of the slits 319 and also the low dielectric constant portion338 a is arranged in the area opposing to the slit 319, as shown in FIG.57, the disclination is generated as the singular point of the alignmentstate in the indefinite positions from the edge of the high dielectricconstant portion 338 b to the slit 319 (e.g., position encircled by abroken line in FIG. 57). Thus, there are caused the problems such thatthe display luminance is dark, the response is slow, etc. Accordingly,the low dielectric constant portion 338 a must be arranged in the middleof the slits 319, the high dielectric constant portion 338 b must bearranged in the position opposing to the slit 319, and the difference inthe relative dielectric constant between the low dielectric constantportion 338 a and the high dielectric constant portion 338 b must be setto more than 0.5.

[0393]FIGS. 58A and 58B and FIG. 59 show a variation of the eighteenthembodiment respectively. FIG. 58A shows an example in which the lowdielectric constant portion 338 a is arranged in parallel with the gatebus line 312 in the middle of the pixel. FIG. 58B shows an example inwhich the low dielectric constant portion 338 a is arranged in parallelwith the drain bus line 315 in the middle of the pixel. In both cases,the dielectric film is formed on the opposing substrate side and thedifference in the relative dielectric constant between the portion withthe high dielectric constant and the portion with the low dielectricconstant is set to more than 0.5. Accordingly, like the eighteenthembodiment, the disclination can be prevented.

[0394]FIG. 59 shows an example in which portions 338 c with the middledielectric constant (relative dielectric constant is 3.25) are arrangedbetween the low dielectric constant portion 338 a (relative dielectricconstant is 3) arranged in the middle of the slits 319 and the highdielectric constant portion 338 b (relative dielectric constant is 3.5)arranged to oppose to the slits. In this case, the similar effect to theabove can be achieved.

[0395] In the above embodiments, the case is explained where the slitsare formed in the pixel electrode on the TFT substrate side and thedielectric film having the portions with the different relativedielectric constant is formed on the opposing substrate side. However,if the dielectric film is formed on the TFT substrate side and thedomain defining slits or projections are provided on the commonelectrode on the opposing substrate side, the same effect as the aboveembodiments can be obtained. Also, the dielectric film having theportions with the different relative dielectric constant may be formedon both the TFT substrate and the opposing substrate. In this case, theportion of the dielectric film with the low dielectric constant on theopposing substrate side is arranged so as to oppose to the portion ofthe dielectric film with the high dielectric constant on the TFTsubstrate side, and also the portion of the dielectric film with thehigh dielectric constant on the opposing substrate side is arranged soas to oppose to the portion of the dielectric film with the lowdielectric constant on the TFT substrate side.

[0396] According to the liquid crystal display device of the presentinvention, since the domain defining portions are formed on onesubstrate and the dielectric film having the portion with the highdielectric constant and the portion with the low dielectric constant isformed on the other substrate, the alignment division (multi domains)can be attained by the domain defining portions and the dielectric film.Therefore, the large aperture ratio can be achieved and the good viewingangle characteristic and the good picture quality can be obtained.

What is claimed is:
 1. A vertically aligned liquid crystal displaydevice for controlling liquid crystal molecules alignment in voltageapplication by providing linear structures or linear slits consisting ofa plurality of constituent units to at least one of a pair of substrateshaving an electrode thereon, comprising: alignment controlling means forforming an alignment singular point s=−1 of liquid crystal molecules atan intersecting point between the structures on the electrode or theslits in the electrode and an edge of a pixel electrode on one of thesubstrates.
 2. A liquid crystal display device according to claim 1,wherein the linear structures are formed on the pixel electrode or acommon electrode.
 3. A liquid crystal display device according to claim1, wherein the slits are not formed on the edge of the pixel electrodelocated on prolonged lines of the slits.
 4. A liquid crystal displaydevice according to claim 1, wherein the structure is divided on or overthe edge of the pixel electrode.
 5. A vertically aligned liquid crystaldisplay device for controlling liquid crystal molecules alignment involtage application by providing linear structures or linear slitsconsisting of a plurality of constituent units to at least one of a pairof substrates having an electrode thereon, comprising: alignmentcontrolling means for forming an alignment singular point s=+1 of liquidcrystal molecules at an intersecting point between the structures or theslits formed on one substrate and an edge of a pixel electrode formed onthe other substrate.
 6. A vertically aligned liquid crystal displaydevice for controlling liquid crystal molecules alignment in voltageapplication by providing linear structures or linear slits consisting ofa plurality of constituent units having a bending portion to at leastone of a pair of substrates having an electrode thereon, wherein thebending portions of the structures or the slits on one of the substrateshaving a pixel electrode are put out from the edge of the pixelelectrode.
 7. A vertically aligned liquid crystal display device forcontrolling liquid crystal molecules alignment in voltage application byproviding linear structures or linear slits consisting of a plurality ofconstituent units having a bending portion to at least one of a pair ofsubstrates having an electrode thereon, wherein the bending portions ofthe structures or the slits arranged on the other substrate to oppose toa pixel electrode on one substrate are not arranged on the edge of thepixel electrode.
 8. A thin film transistor substrate comprising: astorage capacitance forming electrode formed on a first substrate; anactive element formed on the first substrate; and a pixel electrodeformed on the first substrate to be connected to the active element, anddivided into at least three areas by slits; wherein electricalconnection of one area of the three areas of the pixel electrode toanother area has a plurality of routes passing through different areas.9. A thin film transistor substrate according to claim 8, wherein atleast two of the routes of the electrical connection are provided tooppose electrically to the storage capacitance forming electrode.
 10. Athin film transistor substrate according to claim 9, wherein areasopposing to the storage capacitance forming electrode are differentevery route opposing to the storage capacitance forming electrode.
 11. Athin film transistor substrate according to claim 9, wherein thicknessesof dielectric layers are different in areas opposing to the storagecapacitance forming electrode every route opposing to the storagecapacitance forming electrode.
 12. A thin film transistor substrateaccording to claim 9, wherein storage capacitance values are differentevery route opposing to the storage capacitance forming electrode.
 13. Aliquid crystal display device including a thin film transistor substrateset forth in any one of claims 8 to
 12. 14. A liquid crystal displaydevice in which liquid crystal having negative dielectric anisotropy issealed between a first substrate and a second substrate, to surfaces ofwhich a vertical alignment process is applied, and alignment of theliquid crystal molecules becomes substantially perpendicular when novoltage is applied, substantially parallel when a predetermined voltageis applied, and oblique when a voltage smaller than the predeterminedvoltage is applied, comprising: a first domain defining means formed ofdielectric projections provided on the first substrate, for defining anoblique alignment direction of the liquid crystal molecules when thevoltage smaller than the predetermined voltage is applied; a seconddomain defining means provided on the second substrate, for defining theoblique alignment direction of the liquid crystal molecules when thevoltage smaller than the predetermined voltage is applied; a pluralityof first bus lines formed on the first substrate or the secondsubstrate; a plurality of second bus lines formed over the first buslines at a distance; a pixel electrode formed in areas that arepartitioned by the first bus lines and the second bus lines; anddielectric structures formed on at least one of the first substrate andthe second substrate in areas to oppose to at least a part of areasbetween the pixel electrode and the first bus lines, the dielectricstructures being different from the projections.
 15. A liquid crystaldisplay device according to claim 14, wherein the projections and thedielectric structures are formed of same material and by same steps. 16.A liquid crystal display device according to claim 14, wherein thedielectric structures are formed on at least one of the first bus linesand the second bus lines.
 17. A liquid crystal display device accordingto claim 14, wherein the second domain defining means are projections toprotrude into a layer of the liquid crystal or slits opened partially inan electrode on a second substrate side.
 18. A liquid crystal displaydevice according to claim 14, wherein a red, green, or blue color filteris formed to oppose to the pixel electrode, and the dielectricstructures are composed of color filters that are overlapped in areasnot opposing to the pixel electrode.
 19. A liquid crystal display deviceaccording to claim 18, wherein the areas not opposing to the pixelelectrode are at least one of areas between the first bus lines and thepixel electrode and areas between the second bus lines and the pixelelectrode.
 20. A liquid crystal display device according to claim 18,wherein another dielectric structures are further superposed on theareas in which the color filters are overlapped.
 21. A liquid crystaldisplay device according to claim 18, wherein another dielectricstructures are formed to oppose to the areas in which the color filtersare overlapped.
 22. A liquid crystal display device according to claim14, wherein the dielectric structures are formed up to areas protrudinginto a part of the pixel electrode.
 23. A liquid crystal display deviceaccording to claim 14, wherein at least one of the first domain definingmeans and the second domain defining means is not provided on an outsideof the pixel electrode, or is not provided in peripheral areasintersecting with at least one of the first bus lines and the second buslines.
 24. A liquid crystal display device according to claim 14,wherein a thickness of the dielectric structures is more than 1 μm. 25.A liquid crystal display device comprising: a first substrate and asecond substrate arranged in parallel with each other at a distance; aliquid crystal layer formed by filling liquid crystal material havingnegative dielectric anisotropy between the first substrate and thesecond substrate; a first electrode and a second electrode formed onopposing surfaces of the first substrate and the second substraterespectively to define a pixel by at least one of them; projectionsformed on the opposing surface of the first electrode; a domain definingmeans formed on the opposing surface of the second electrode, fordefining boundary positions of domains in which tilt directions ofliquid crystal molecules are uniform together with the projections; analignment film formed on at least one of the first substrate and thesecond substrate and having an alignment defining force to align theliquid crystal molecules on a surface of the alignment filmperpendicularly to a film surface; and a compensating means arrangedalong edges of the projections when viewed along a normal direction ofthe first substrate, for reducing a double refraction effect acting on alight, that transmits in a thickness direction of the liquid crystallayer, due to oblique alignment of the liquid crystal molecules of theliquid crystal layer in a neighborhood of the edges of the projections.26. A liquid crystal display device according to claim 25, wherein thecompensating means is formed of optical member which is arranged alongthe edges of the projections on a non-opposing surface of the firstsubstrate and formed of material having refractive anisotropy.
 27. Aliquid crystal display device according to claim 25, wherein theprojections contain a first portion positioned in a neighborhood of theedge and having refractive anisotropy and a second portion positioned ina center portion having no refractive anisotropy or smaller refractiveanisotropy than the first portion respectively, and the first portionsare also used as the compensating means.
 28. A liquid crystal displaydevice comprising: a first substrate and a second substrate arranged inparallel with each other at a distance; a liquid crystal layer formed byfilling liquid crystal material having negative dielectric anisotropybetween the first substrate and the second substrate; a first electrodeand a second electrode formed on opposing surfaces of the firstsubstrate and the second substrate respectively to define a pixel by atleast one of them; an alignment film formed on at least one of the firstsubstrate and the second substrate and having an alignment definingforce to align the liquid crystal molecules of the liquid crystal layerperpendicularly to the film surface; projections formed on the opposingsurface of the first electrode; a first domain defining means providedon the opposing surface of the first electrode and having a patternelongated along one direction in at least a local area within asubstrate surface, and for tilting the liquid crystal molecules in aneighborhood of an edge of the first domain defining means to such adirection that end portions positioned far from the first electrode goaway from the first domain defining means when a voltage is appliedbetween the first electrode and the second electrode; and a seconddomain defining means provided on the opposing surface of the secondelectrode and arranged in parallel with or to be overlapped with thefirst domain defining means in at least a local area within thesubstrate surface when viewed along a normal direction of the substrate,and for tilting the liquid crystal molecules on an inside of the seconddomain defining means to a direction that is substantially parallel witha length direction of the second domain defining means.
 29. A liquidcrystal display device according to claim 28, wherein the first domaindefining means contains projections formed of dielectric material formedon the first electrode or slits formed in the first electrode, and thesecond domain defining means contains projections formed on the opposingsurface of the second substrate and having a conductive surface, areasof the alignment film which are formed on the opposing surface of thesecond substrate and in which an alignment defining force is destroyedor weakened, or recess patterns on the surface of the dielectric filmformed on the opposing surface of the second substrate.
 30. A liquidcrystal display device according to claim 28, further comprising: athird domain defining means formed on the opposing surface of the firstsubstrate to extend in a direction orthogonally intersecting with thefirst domain defining means in at least a local area within thesubstrate surface, and for tilting the liquid crystal molecules of theliquid crystal layer in a neighborhood of an edge of the third domaindefining means to such a direction that end portions positioned far fromthe first electrode go away from the third domain defining means whenthe voltage is applied between the first electrode and the secondelectrode.
 31. A liquid crystal display device comprising: a firstsubstrate and a second substrate arranged in parallel with each other ata distance; a liquid crystal layer formed by filling liquid crystalmaterial having negative dielectric anisotropy between the firstsubstrate and the second substrate; a first electrode and a secondelectrode formed on opposing surfaces of the first electrode and thesecond electrode respectively to define a pixel by at least one of them;and an alignment film formed on at least one of opposing surfaces of thefirst substrate and the second substrate, and defined into first areascontaining at least two parallel patterns elongated in one direction anda second area between the first areas, the second area having analignment defining force to align liquid crystal molecules of the liquidcrystal layer perpendicularly to the substrate surface and the firstareas having no alignment defining force or a weaker alignment definingforce than the alignment defining force in the second area.
 32. A liquidcrystal display device according to claim 31, wherein a chiral agent isadded into the liquid crystal layer.
 33. A liquid crystal display devicecomprising: a first substrate and a second substrate arranged inparallel with each other at a distance; a liquid crystal layer formed byfilling liquid crystal material having negative dielectric anisotropybetween the first substrate and the second substrate; a first electrodeand a second electrode formed on opposing surfaces of the firstelectrode and the second electrode respectively to define a pixel by atleast one of them; and an alignment film formed on at least one ofopposing surfaces of the first substrate and the second substrate, anddefined into first areas extended from respective corners of the pixelto an inside of the pixel to have patterns connected mutually and asecond area partitioned by the first areas and edges of the pixel, thesecond area having an alignment defining force to align liquid crystalmolecules of the liquid crystal layer perpendicularly to the substratesurface and the first areas having no alignment defining force or aweaker alignment defining force than the alignment defining force in thesecond area.
 34. A liquid crystal display device comprising: a firstsubstrate on which a first electrode and bus lines for transmitting asignal to the first electrode are formed; a second substrate on which asecond electrode is formed; domain defining projections provided on oneof the first substrate and the second substrate; a plurality of domaindefining slits provided on an electrode on the other of the firstsubstrate and the second substrate to be aligned on a straight line; afirst alignment film for covering the first electrode; a secondalignment film for covering the second electrode; and liquid crystalsealed between the first substrate and the second substrate and havingnegative dielectric anisotropy; wherein a pre-tilt angle revealingprocess is applied to the alignment film on the other substrate in anarea in which alignment of liquid crystal molecules becomes unstable bya lateral electric field from the bus line.
 35. A liquid crystal displaydevice according to claim 34, wherein the pre-tilt angle revealingprocess sets a pre-tilt angle at an interface between the alignment filmand the liquid crystal to more than 45 degrees but less than 90 degreeswhen no voltage is applied.
 36. A liquid crystal display deviceaccording to claim 34, further comprising: auxiliary projectionsprovided on one substrate to be arranged along the edge of the electrodeon the other substrate.
 37. A liquid crystal display device according toclaim 36, wherein the pre-tilt angle revealing process is applied toareas in which an angle between the domain defining projections and theedge of the pixel electrode is an obtuse angle.
 38. A liquid crystaldisplay device according to claim 34, wherein the pre-tilt anglerevealing process is applied to a bus line side areas in the slits whoseend portions on the bus line side are closed and which are positionedclosest to the bus line.
 39. A liquid crystal display device comprising:a first substrate on which a first electrode and a bus line fortransmitting a signal to the first electrode are formed; a secondsubstrate on which a second electrode is formed; domain definingprojections provided on one of the first substrate and the secondsubstrate; a plurality of domain defining slits provided on theelectrode on the other of the first substrate and the second substrateto be aligned on a straight line; and liquid crystal sealed between thefirst substrate and the second substrate and having negative dielectricanisotropy; wherein a width of a bus line opposite side end of a firstslit of the plurality of slits, that is positioned closest to the busline, is set smaller than a width of a bus line side end of a secondslit positioned adjacent to the first slit.
 40. A liquid crystal displaydevice according to claim 39, further comprising: auxiliary projectionsprovided on one substrate to be arranged along the edge of the electrodeon the other substrate.
 41. A liquid crystal display device comprising:a first substrate on which a first electrode and a bus line fortransmitting a signal to the first electrode are formed; a secondsubstrate on which a second electrode is formed; domain definingprojections provided on one of the first substrate and the secondsubstrate; a plurality of domain defining slits provided on theelectrode on the other of the first substrate and the second substrateto be aligned on a straight line; a first alignment film for coveringthe first electrode; a second alignment film for covering the secondelectrode; and liquid crystal sealed between the first substrate and thesecond substrate and having negative dielectric anisotropy; wherein apre-tilt angle revealing process is applied to the alignment film on theother substrate in an area in which alignment of liquid crystalmolecules becomes unstable by a lateral electric field from the busline, and a width of a bus line opposite side end of a first slit of theplurality of slits, that is positioned closest to the bus line, is setsmaller than a width of a bus line side end of a second slit positionedadjacent to the first slit.
 42. A liquid crystal display device in whichliquid crystal is sealed between a pair of substrates on whichelectrodes are provided, wherein a domain defining portion is providedon one substrate of the pair of substrates, a dielectric film having ahigh dielectric constant portion and a low dielectric constant portionis provided on the other substrate of the pair of substrates, and thehigh dielectric constant portion is arranged at positions in an obliquedirection to the domain defining portion and the low dielectric constantportion is arranged at positions opposing to the domain definingportion, and difference in a relative dielectric constant between thehigh dielectric constant portion and the low dielectric constant portionis more than 0.5.
 43. A liquid crystal display device according to claim42, wherein slits are formed in the electrode on one substrate as thedomain defining portion.
 44. A liquid crystal display device accordingto claim 42, wherein projections are provided on one substrate as thedomain defining portion.
 45. A liquid crystal display device accordingto claim 42, wherein dielectric constant is changed stepwise between thehigh dielectric constant portion and the low dielectric constantportion.